Name: experimental procedure for warm spinning of cast aluminum components
Uploaded: 2017-02-01T15:00:00.000+00:00
Duration: 7 min 36 s
Description: Watch this Scientific Journal Video about Experimental Procedure for Warm Spinning of Cast Aluminum Components at JoVE.com

<p class="jove_content"> Los autores desean agradecer a Ross McLeod, David Torok, Wonsang Kim y Carl Ng por su apoyo técnico. MJ Roy le gustaría reconocer el apoyo de EPSRC (EP / L01680X / 1) a través de los materiales para los exigentes entornos Centro de formación de doctorado y Rio Tinto Alcan para el apoyo financiero a través de un premio de beca de investigación. </p>

<p class="jove_title"> 1. Preparación de pieza de trabajo para la formación de Ensayos </p><ol><li> Adquirir piezas de trabajo como a cielo mecanizadas con el tamaño de mandril de tal manera que el descentramiento del diámetro interior es de 0,2 mm, mientras que el diámetro exterior retiene tanta superficie de molde como sea posible. <br /> NOTA: Si piezas en bruto se extraen de piezas de fundición de la rueda de tamaño completo, se requieren operaciones de mecanizado para eliminar todo el concentrador y radio porciones, mientras que proporciona características que pueden ser empleados para sujetar la pieza de trabajo en el mandril. Esto incluye la eliminación de la brida en la placa base. </li><li> Pre-calentar un horno ataúd capaz de recibir toda la pieza de trabajo a 135 ° C, limpiar la pieza de trabajo con desengrasante y el lugar en el horno durante una hora para prepararse para aplicación del recubrimiento de barrera térmica. </li><li> Eliminar rápidamente la pieza del horno y colocar en una plantilla de recubrimiento. El uso de un pulverizador de pintura de tipo automóvil, aplicar una capa delgada de revestimiento con matriz de barrera térmica con el diámetro interior. <br /> NOTA: Este revestimiento proporcionará la lubricación y reducir la transferencia de caloral mandril durante las operaciones de conformado. </li></ol><p class="jove_title"> 2. Preparación de herramientas </p><ol><li> Limpie la superficie del mandril con un paño húmedo. Asegúrese de que el mandril tiene un descentramiento de rotación total de &lt;0,5 mm utilizando un indicador de reloj de medición a lo largo de la longitud de conformado. Evaluar esto con un centro de herramientas motorizadas participado en la placa de cabezal móvil. Usando una llave de torsión, asegúrese de que todos los sujetadores, aparte de los de los conjuntos de sujeción están apretados al par que se indican los valores de Grado 12.9 pernos (Nm: M8 - 40, M12 - 135, M16 - 340). </li><li> Iniciar el sistema de precalentamiento por la puesta en primer lugar el solenoide de suministro de gas, y luego encender las antorchas con un pedernal encendedor de chispa. Ejecutar el sistema de pre-calentamiento durante 10 minutos para expulsar cualquier condensado recogido en las antorchas / mangueras. Extinguir desactivando el solenoide de suministro de gas. </li><li> Retire la capa de recubrimiento suelta / oxidado en el mandril con papel de carburo de silicio de grano 600 / P1200 seca mientras gira el mandril a 20 revoluciones por minuto(Rpm). </li><li> Alimentar el módulo de adquisición de datos a bordo, y ejecutar el sistema de precalentamiento hasta que los termopares incrustadas en la superficie del mandril leen 200 ° C con el centro dedica vivo. </li><li> El uso de un pulverizador de pintura de tipo automoción, cubrir ligeramente la superficie del mandril con un lubricante de forjado a base de agua y permitir que la herramienta rotativa se enfríe a temperatura ambiente con el centro de herramientas motorizadas activado. </li><li> Afloje el conjunto de tuerca de seguridad en el soporte de rodillos <strong>(Figura 3)</strong> con una llave. Ajuste el enfoque o el ángulo de ataque contra el conjunto de rodillo utilizando un transportador de un fabricante de herramientas, y apriete ambas tuercas internas y externas (M35 - 750 nm). </li><li> Montar los conjuntos de abrazadera 3 <strong>(Figura 4)</strong> por primera enganchar el perno de tope M12 para conectar el elemento 2 para el soporte de fijación. Inspeccionar cualquier distorsión térmica que evitará que el elemento 2 en la <strong>Figura 4</strong> de correr suavemente contra el soporte de fijación. Asegúrese de que se mueven libremente, es ligeramenteAND de las superficies de contacto con papel de carburo de silicio de grano 320 / P400 en seco. Aplicar una capa fina de alta temperatura lubricante a base de molibdeno con un paño, según sea necesario. </li></ol><p class="jove_title"> 3. Las operaciones de formado </p><ol><li> Mover la herramienta de soporte de rodillo completamente del mandril hacia el husillo, mover el cabezal móvil y el centro para ser claros del mandril. deslice manualmente la pieza de trabajo sobre el mandril asegurando incluso compromiso. <br /> Nota: Como los espacios en blanco son nominalmente de revolución, no hay ninguna orientación preferida. </li><li> Montar las abrazaderas sobre el mandril mediante la participación de los pasadores cónicos de matriz y de la mano de apretar los pernos M16 que se ejecutan a través del mandril en los bloques de sujeción. Asegúrese de que hay incluso presión que se aplica mediante la rotación manual de apriete, seguido de una llave de impacto neumática establece en 50 Nm. </li><li> Iniciar el sistema de calefacción y comenzar inmediatamente el mandril que gira a 20 revoluciones por minuto. Mantener la aplicación de calor hasta que las abrazaderas se suelten. Para el proceso considerado, esto es apmadamente 3 min. <br /> NOTA: Esta vez será un poco diferente para cada pieza de trabajo debido a las diferencias sutiles en el montaje de la pieza / mandril. </li><li> Extinguir el sistema de calefacción y detener la rotación del mandril de manera que la primera abrazadera es accesible con una llave de impacto. Dentro de los 30 s, apriete todas las abrazaderas con una llave de impacto o manual y grabar la temperatura de la superficie de la pieza de trabajo en 3 lugares a lo largo de la longitud de la región de formación con una sonda termopar tipo Reed. </li><li> Repita el paso 3.4 hasta que la pieza de trabajo está a una temperatura de formación adecuada; como mínimo, 350 ° C para A356. Realizar un ajuste final de las abrazaderas con una llave de impacto conjunto de 200 Nm. </li><li> Mover el rodillo axial y radialmente (aprox. 2-5 mm de la superficie de la pieza de trabajo) en su posición para formar y realizar una última abrazadera de apriete <em>(es decir,</em> el paso 3.4). </li><li> Con el sistema de calefacción en, aumentar la velocidad de rotación del torno a la velocidad de formación de la intención, participar el rodillo parauna profundidad pre-establecido en la pieza de trabajo, y activar la alimentación de corte de tornillo para mover el rodillo axialmente a lo largo de la longitud de la pieza de trabajo. <br /> NOTA: Para el presente geometría, resultados razonables se han obtenido en 281 rpm con un movimiento axial de 0,21 mm / vuelta. </li><li> Repita el paso 3.7 como se requiere para aumentar los niveles de deformación. Después de cada pasada de conformación, asegurar que la temperatura no descienda por debajo de la temperatura de formación óptima al detener el mandril y usando la misma sonda de termopar de tipo caña, como se emplea en el paso 3.4. Si la temperatura de formación óptima se ha reducido, repita los pasos 3.4 y 3.5 para recalentar. <br /> NOTA: El recalentamiento se puede emplear, sin embargo, a expensas de alcanzar potencialmente la extensión de la capacidad del sistema de pinza para sujetar la pieza de trabajo. </li></ol><p class="jove_title"> 4. Operaciones vástago de formación </p><ol><li> Una vez se ha obtenido el nivel deseado de deformación, detener el sistema de calefacción, y deshacer todas las abrazaderas, y desenganchar el cabezal móvil para obtener CLEarance para la eliminación de la pieza de trabajo. </li><li> Golpear suavemente la pieza de trabajo con una pieza de latón para separarse del mandril. Si esto resulta ser ineficaz, vuelva a activar el sistema de calefacción y girar el mandril a 20 rpm golpeando suavemente hasta que los separa en blanco. </li><li> El uso de una herramienta de manipulación apropiada, tal como pinzas o guantes aislados en gran medida, ya sea apagar la pieza en agua a 60 ° C para prevenir el envejecimiento adicional, o dejar enfriar al aire para minimizar el estrés residual / distorsión. </li></ol>

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<p class="jove_content"> Los autores no tienen nada que revelar. </p>

<p class="jove_content"> Los resultados representativos mostrados anteriormente ponen de manifiesto que el protocolo y el material empleado es capaz de formar aluminio fundido a temperaturas elevadas, y ha proporcionado una plataforma para determinar una ventana de procesamiento para la formación de las ruedas de flujo. La técnica mostrada se puede utilizar para explorar aspectos de la formación de sobres, incluyendo la forma en tanto formado y el material sin forma responde a tratamiento térmico <sup class="xref">8.</sup> Sin embargo, hay espacio para la mejora con el protocolo de tratamiento actual con este aparato. </p><p class="jove_content"> En cuanto a la instrumentación más, lo que aceleraría el desarrollo del modelo de proceso, la inclusión de un dinamómetro de máquina-herramienta y tribómetros <sup class="xref"><sup>11,</sup></sup> <sup class="xref">12</sup> para medir la formación de cargas y factores de fricción en el rodillo proporcionaría información importante acerca de las condiciones del proceso. Esta es una técnica ampliamente la instrumentación empleada para estudios de mecanizado ortogonales, y podríaimplementarse fácilmente en el equipo actual. Esta instrumentación adicional proporcionaría datos útiles para validar la precisión de los esfuerzos de modelado <sup class="xref"><sup>13,</sup></sup> <sup class="xref">14</sup> y apoyar el creciente interés industrial en este proceso. Con el fin de capturar de manera efectiva la evolución de la temperatura de la pieza en bruto durante el procesamiento, una técnica de medición sin contacto es deseable. Sin embargo, las técnicas basadas en infrarrojos comunes se ven obstaculizados por la baja emisividad de aluminio y cómo los cambios en la superficie durante el procesamiento. Esta es la razón principal por la cual un instrumentados, puesta en marcha en blanco fue empleado para capturar la típica respuesta térmica conseguido con el protocolo descrito, y sirvieron para rellenar un análisis de transferencia de calor de línea de base para relacionar la temperatura superficial del mandril a la pieza de trabajo. </p><p class="jove_content"> Ya que es en gran medida un proceso de formación manual de un material que es sensible al tiempo a la temperatura, algunas inconsistencias entre una ejecución a otra sonse espera. Las aleaciones de aluminio tienen microestructuras que son altamente sensibles a temperaturas superiores a 100 ° C debido a los mecanismos de envejecimiento. Por lo tanto, los pasos más críticos dentro del protocolo son 1.2 y 3.3 a 3.7, donde la pieza en bruto es a temperaturas elevadas. Apriete y re-asientos las abrazaderas deben llevarse a cabo lo más rápidamente posible para mantener la repetibilidad entre las operaciones de formación. </p><p class="jove_content"> La calefacción <em>en</em> la pieza de trabajo <em>situ</em> empleado durante la etapa de pre-calentamiento es bastante ineficiente y podría mejorarse a través de la calefacción por radiación. Las velocidades de procesamiento general en términos de movimientos de mandril y de herramientas que se pueden alcanzar son algo limitadas por las capacidades del torno empleado. velocidades más altas requieren que forman un marco más rígido con una capacidad de carga más alta, en particular si la formación de un material más fuerte se intentara. de sujeción de piezas de trabajo y pueden ser mejoradas con la adición de accionamiento hidráulico o neumático. Como la transferencia de calor desde el blank al mandril es en gran medida una función de la presión impuesta por la pieza de trabajo sobre el mandril, de esta adición también podría mejorar un enfoque basado en modelos para determinar la temperatura de la pieza de trabajo durante la formación con el sistema existente. </p><p class="jove_content"> El aparato y el procedimiento descrito se ha demostrado que la formación de cargas de este material en estas condiciones se aproxima a los de las operaciones de torneado estándar, y sigue siendo un proceso muy rentable por el cual para llevar a cabo los ensayos de fabricación. La investigación en diferentes rutas de fabricación y capacidad de conformación puede llevarse a cabo fuera de un equipo de formación comercial, que es muy caro de operar. Con el aparato y el protocolo descrito, los parámetros de procesamiento pueden ser investigados antes de construir a mayor escala, un equipo de mayor rendimiento, y al conocimiento de los autores, es un enfoque único. </p><p class="jove_content"> Como el protocolo desarrollado sólo se ha aplicado a una variante específica de aleación de aluminio fundido, laRE es una multitud de otras aleaciones de fundición de aluminio, que podría ser investigados para una variedad de aplicaciones más allá de las ruedas del automóvil. A medida que estas aleaciones tienen ventanas de procesamiento de aproximadamente similares desde una perspectiva de la temperatura, el protocolo desarrollado se puede adaptar fácilmente. </p>

<p class="jove_content"> Una de las operaciones de formación de metales más difíciles que actualmente se practican en los sectores aeroespacial y del transporte es el hilado de metal, incluyendo derivados, tales como la formación de cizallamiento y de flujo que forma <sup class="xref"><sup>1,</sup></sup> <sup class="xref">2.</sup> En este proceso, una pieza de trabajo de revolución se coloca sobre un mandril que representa la forma final deseada, y se dio en contacto con uno o más incide rodillos. La pieza de trabajo que está siendo comprimido entre el rodillo y el mandril a continuación se deforma plásticamente, con una respuesta diversa, incluyendo la flexión elongación combinada, adelgazamiento y axial. En un material que tiene una ductilidad limitada o es de otro modo difícil de formar, esto se lleva a veces a una temperatura elevada para disminuir el estrés de flujo y el aumento de la ductilidad. </p><p class="jove_content"> Desde un punto de vista de procesamiento, hay una amplia gama de parámetros que pueden dictar la forma y propiedades del componente fabricado. Numerosos estudios se han centradoen técnicas estadísticas para la optimización de varios parámetros de <sup class="xref"><sup>3,</sup></sup> <sup class="xref"><sup>4,</sup></sup> <sup class="xref">5.</sup> Las variables incluyen la geometría de herramientas, tales como la forma de la herramienta y el mandril; formación de velocidades incluyendo tanto las tasas de velocidad de rotación del mandril y piensos utillaje; así como las propiedades del material. Cuando se requieren temperaturas elevadas, los profesionales necesitan para evaluar la temperatura mínima necesaria al tiempo que conserva un producto de sonido. </p><p class="jove_content"> aleaciones de fundición de aluminio se emplean en una amplia variedad de aplicaciones de automoción y aeroespacial, con el A356 aleación utilizada en las ruedas del automóvil. Sin embargo, esta aleación no es adecuado para formar a temperatura ambiente <sup class="xref"><sup>6,</sup></sup> <sup class="xref">7</sup> debido a su ductilidad limitada y debe formarse a temperaturas elevadas. Esto introduce una gran cantidad de procesamiento de la complejidad, principalmente en el control de la temperatura. Como las propiedades de este material de cambio de SIGNIFICAntly con la temperatura <sup class="xref">8,</sup> es particularmente importante realizar ensayos instrumentados en el que las condiciones térmicas se pueden mantener dentro de una ventana de procesamiento razonable y ser monitoreados. Los datos detallados sobre el comportamiento termomecánico de A356 de colada que van desde la temperatura ambiente hasta 500 ° C en un amplio intervalo de velocidades de deformación pueden ser revisados ​​en otro lugar. <sup class="xref">9</sup> </p><p class="jove_content"> Con el fin de apoyar el desarrollo y la optimización de las operaciones para la fabricación rueda de formación de flujo, que forman el equipo costumbre se ha desarrollado en el Departamento de Ingeniería de Materiales de la Universidad de Columbia Británica <strong>(Figura 1).</strong> Este aparato se ha construido principalmente de un torno cabestrante manual, accionado por correa con una potencia total de 22 kW, y un sistema de calefacción de propano antorcha con una potencia máxima de 82 kW <strong>(Figura 2).</strong> Un mandril con termopares integrados junto con un conjunto de rodillo rígida <strong>(Figura 3)</strong> ha sidoinstalada, que es capaz de formar piezas de trabajo hasta 330 mm de diámetro. El mandril tiene un sistema de sujeción de accionamiento manual que es capaz de dar cuenta de grandes cambios en el diámetro de la pieza que se producen durante el procesamiento <strong>(Figura 4).</strong> Una batería operado sistema de adquisición de datos (DAQ) que contiene un ordenador inalámbrico miniatura capaz de monitorizar la temperatura del mandril durante la formación y la pieza en bruto para la calefacción caracterización se ha instalado en la pluma del torno. Mientras que otros procesos de formación de flujo se han sintetizado usando tornos adaptados <sup class="xref"><sup>4,</sup></sup> <sup class="xref">10,</sup> el presente aparato es el primero a encarnar <em>en la</em> calefacción <em>situ</em> y datos térmicos adquisición. </p><p class="jove_content"> Un protocolo de procesamiento para las operaciones de formación a escala industrial-ha sido desarrollado para proporcionar las condiciones de procesamiento indicativos. Se describe posteriormente, este protocolo consiste en herramientas y preparación de la pieza, que forma práctica, concluding con el extremo de formación de operaciones de prueba. </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="Figura 1" src="/files/ftp_upload/55061/55061fig1.jpg" /><br /> <strong>Figura 1:</strong> <strong>Información general del aparato experimental.</strong> componentes principales que se han añadido a un torno cabrestante modificada para formar a temperaturas elevadas. Fotografía del equipo (arriba) y de las principales direcciones de trabajo y componentes etiquetados en una representación de diseño asistido por ordenador (parte inferior). <a href="http://ecsource.jove.com/files/ftp_upload/55061/55061fig1large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="Figura 2" src="/files/ftp_upload/55061/55061fig2.jpg" /><br /> <strong>Figura 2: Calefacción detalle del sistema.</strong> Un sistema de calefacción de propano con cuatro quemadores discretos (superior e inferior derecha) accionadas desde un colector central que contiene un solenoide de control de gas (parte superior e inferior izquierda).La presión de gas y un caudal discreto a cada uno de los quemadores es posible, junto con la colocación a lo largo de la pieza en bruto para ajustarse a diferentes geometrías. <a href="http://ecsource.jove.com/files/ftp_upload/55061/55061fig2large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="figura 3" src="/files/ftp_upload/55061/55061fig3.jpg" /><br /> <strong>Figura 3:</strong> <strong>Soporte de rodillos detalle el montaje.</strong> El titular de la herramienta original por el torno ha sido adaptado para sostener un rodillo en arbitraria ángulos con respecto al eje de giro del mandril a través de un conjunto de tuerca de atasco. <a href="http://ecsource.jove.com/files/ftp_upload/55061/55061fig3large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="Figura 4" src="/files/ftp_upload/55061/55061fig4.jpg" /><br /> <strong>Figura 4:</strong> <strong&gt; Mandril instrumentada y visión general del sistema de sujeción. El herramientas rotativas ha sido diseñado para atornillar directamente al husillo del torno, que es a su vez el apoyo de un centro vivo en el cabezal móvil (arriba y abajo izquierda). conjunto de abrazadera / operación también se muestra (arriba y abajo a la derecha). <a href="http://ecsource.jove.com/files/ftp_upload/55061/55061fig4large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> </p>

<table><tbody><tr><td>&lt;strong&gt;Reagent/Material&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>High temperature grease</td><td>Dow Corning</td><td>Molycote M-77</td><td></td></tr><tr><td>High temperature lubricant</td><td>Superior Graphite</td><td>sureCOAT</td><td></td></tr><tr><td>High temperature die coat</td><td>Vesuvius/Foseco</td><td>DYCOTE 32</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Live center</td><td>Riten Industries</td><td>17124</td><td>Bell-head, spring loaded</td></tr><tr><td>Live center adapter</td><td>Riten Industries</td><td>431</td><td>Adapter for lathe</td></tr><tr><td>Impact wrench</td><td>Chicago Pneumatic</td><td>CP7749-2</td><td>1/2&quot; drive, 0-545 ft-lb</td></tr><tr><td>Torque wrench</td><td>Westward Tools</td><td>6PAG0</td><td>1/2&quot; drive, 0-250 ft-lb</td></tr><tr><td>Air-powered paint sprayer</td><td>Cambell Hausfeld</td><td>DH4200</td><td>For die coat</td></tr><tr><td>Air-powered paint sprayer</td><td>Cambell Hausfeld</td><td>DH5500</td><td>For graphite-based lubricant, high volume low pressure (HVLP) type</td></tr><tr><td>Data acquisition unit</td><td>Measurement Computing</td><td>USB-2416</td><td></td></tr><tr><td>Reed thermocouple</td><td>Omega Engineering</td><td>88108</td><td></td></tr><tr><td>Propane tank</td><td>Generic</td><td></td><td>20/40 lb, POL fitted</td></tr><tr><td>Solenoid valve</td><td>Aztec Heating</td><td>SV-S121</td><td></td></tr><tr><td>Gas regulator</td><td>Aztec Heating</td><td>67CH-743</td><td>0-30 psi</td></tr><tr><td>Burner tips</td><td>Exact</td><td>3119</td><td>Qty: 4</td></tr><tr><td>Roller bearings</td><td>SKF</td><td>32005 X/Q</td><td>Qty: 2</td></tr><tr><td>Remaining equipment designed and fabricated in-house</td><td></td><td></td><td></td></tr></tbody></table>

experimental procedure for warm spinning of cast aluminum components

<p class="jove_content"> Alto rendimiento, las ruedas de automóviles de aluminio fundido cada vez más se están formando de forma incremental a través de la formación de flujo / hilado de metal a temperaturas elevadas para mejorar las propiedades del material. Con una amplia gama de parámetros de procesamiento que puede afectar tanto a la forma alcanzada y propiedades de los materiales resultantes, este tipo de procesamiento es muy difícil de comisión. Una versión simplificada, de poca potencia del proceso se ha diseñado e implementado para ruedas de automóviles de tamaño completo. El aparato está destinado a ayudar en la comprensión de los mecanismos de deformación y la respuesta material a este tipo de procesamiento. Un protocolo experimental se ha desarrollado para prepararse, y posteriormente realizar ensayos de conformación y se ha descrito para los espacios en blanco de la rueda A356 de colada. El perfil térmico alcanza, junto con se proporcionan detalles de instrumentación. Se discute la similitud con las operaciones que imparten significativamente más deformación a velocidades más rápidas de formación a gran escala. </p>

<p class="jove_content" fo:keep-together.within-page="1"> Como piezas de fundición de aluminio A356 se formaron de acuerdo con el método descrito en este documento. Las piezas de trabajo se obtuvieron de ruedas bruto de colada de un fabricante de ruedas de América del Norte que emplea la coquilla a baja presión proceso de fundición. Una pieza de trabajo equipada con termopares no se formó, pero sufrió el ciclo de pre-calentamiento (Protocolo de la Sección 3, los pasos 3.3 a 3.5) para capturar la distribución de temperatura a través de la superficie de la pieza en bruto durante este aspecto del proceso. Esta respuesta se muestra en la <strong>Figura 5.</strong> Otros 3 muestras se deforman a varios niveles, incluyendo uno que recibió dos pasadas de laminación para un alto nivel de deformación. Las dos primeras muestras y la primera pasada se realiza en la última muestra sirve para enderezar la pieza de trabajo con poco cambio demostrable en espesor de pared. La reducción de espesor de pared pico última muestra fue de aproximadamente 10%, la mayoría de los cuales se logró en el segundo pass. Las secciones transversales y microestructura del estado bruto de colada en blanco y los obtenidos en la muestra de pasos múltiples se muestran en la <strong>Figura 6.</strong> Aquí, se muestra la microestructura de colada para ser refinado de manera significativa por el proceso con las características dendríticas apenas discernibles. La eutéctica interdendrítico se divide por la deformación impuesta, la creación de una microestructura mucho más homogénea que en el estado bruto de colada. Esto mejora la ductilidad general, así como propiedades de fatiga y fractura del componente. Los autores han descrito previamente más detalles de la geometría de la pieza de trabajo, cambios de sección transversal específicas de espesor de pared, defectos observados, y la variación dimensional en la microestructura en el conjunto completo de muestras de <sup class="xref"><sup>8,</sup></sup> <sup class="xref">13.</sup> </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="Figura 5" src="/files/ftp_upload/55061/55061fig5.jpg" /><br /> <strong>Figura 5:</strong> <strong>Perfil de temperatura típica de mandril y b</strong><html> alto y delgado. Una respuesta térmica transitoria representante de la pieza en bruto y el mandril obtiene con el sistema de calefacción. Vertical líneas discontinuas indican dónde se reforzaron pinzas durante las etapas de precalentamiento, y la flecha negro representa la formación. La última línea vertical muestra cuando el sistema de calefacción se apaga mientras se enfriaba el sistema. </p><p class="jove_content" fo:keep-together.within-page="1"><img alt="Figura 6" src="/files/ftp_upload/55061/55061fig6.jpg" /><br /> <strong>Figura 6: Como resultado fundido y formado.</strong> El como se recibe, la superficie en blanco y la geometría de colada que tiene un diámetro interior mínimo de 330 mm (arriba) se deformó en dos pasadas para proporcionar el resultado se muestra (en el centro). La microestructura dendrítica de colada (parte inferior izquierda) se modifica de forma visible por la operación de formación y un tratamiento térmico T6 posterior (parte inferior derecha) tal como se observó con el microscopio óptico <sup class="xref"><sup>8,</sup></sup> <sup class="xref">13.</sup>ig6large.jpg &quot;target =&quot; _ blank &quot;&gt; Haga clic aquí para ver una versión más grande de esta figura. </p>

Watch this Scientific Journal Video about Experimental Procedure for Warm Spinning of Cast Aluminum Components at JoVE.com

Experimental Procedure for Warm Spinning of Cast Aluminum Components

<p class="jove_content"> Se presenta un protocolo experimental para rotatoria instrumentada cálida formación de aleaciones de aluminio fundido que emplean un aparato de medida en escala industrial. Se discuten consideraciones experimentales incluidos los efectos térmicos y mecánicos, así como la similitud con el procesamiento a gran escala de las ruedas del automóvil. </p>

Procedimiento experimental para hacer girar caliente de fundición, componentes de aluminio

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to ...

experimental-procedure-for-warm-spinning-of-cast-aluminum-components

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JoVE Journal

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Unit 1

Rotation and Rigid Bodies

SCIENTISTS IN ACTION

9.4K vistas.  University of Manchester.  Se presenta un protocolo experimental para rotatoria instrumentada cálida formación de aleaciones de aluminio fundido que emplean un aparato de medida en escala industrial. Se discuten consideraciones experimentales incluidos los efectos térmicos y mecánicos, así como la similitud con el procesamiento a gran escala de las ruedas del automóvil. 

Video: Experimental Procedure for Warm Spinning of Cast Aluminum Components

Enthalpy of Reaction

Enthalpy of Reaction and Measurement of Heat by Calorimeter - procedure

Entalpía de reacción

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Collecting Data for Calculating the Heat Capacity of a CalorimeterExpand
	This experiment will ...

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Metal Flame Emission

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Metal Flame Emission Testing<button class="expand">Expand</button>
	<p>In this lab, you will excite the electrons of six metal chloride salts with heat from a flame and measure the wavelength of light emitted by the relaxing electrons. The emitted light is in the visible spectrum, so you will see different colored flames for the different metals.</p>
	<p>At the end of the lab, you will measure the emission spectrum of a sparkler and use the data you collected from the metal salts to identify the metals in the sparkler. To help with this process, make a table in your lab notebook to record the wavelengths emitted from ambient light, the salts, and the sparkler.</p>
	<h4><strong>Table 1: Observed Wavelengths</strong></h4>
	<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
		<tbody>
			<tr>
				<td style="text-align: center;"><strong>Run #</strong></td>
				<td style="text-align: center;"><strong>Source</strong></td>
				<td style="text-align: center;"><strong>Recorded wavelength(s)</strong></td>
			</tr>
			<tr>
				<td style="text-align: center;">1</td>
				<td style="text-align: center;">Room lights</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">2</td>
				<td style="text-align: center;">NaCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">3</td>
				<td style="text-align: center;">LiCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">4</td>
				<td style="text-align: center;">KCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">5</td>
				<td style="text-align: center;">SrCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">6</td>
				<td style="text-align: center;">BaCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">7</td>
				<td style="text-align: center;">CuCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">8</td>
				<td style="text-align: center;">Sparkler</td>
				<td></td>
			</tr>
		</tbody>
	</table>
	<p><a href="https://www.jove.com/CDNSource/lm/labs/48/Table_1._Observed_Wavelengths.xlsx" target="_blank">Click Here to download Table 1</a></p>
	<p>During this lab, you will hold a salt-coated applicator at the edge of a Bunsen burner flame to excite the metal salts. If the applicator catches fire, immediately quench it in a beaker of water. For excitation, you will hold a detector near the flame and the sparkler to measure the wavelengths of the emitted light. Keep a safe distance to protect yourself and the detector. As some tasks are performed simultaneously, we suggest that you work in groups of four with each student completing tasks as needed.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-4">
		<div class="lab-step">Put on a lab coat, safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Set up the Bunsen burner in the fume hood.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Fill a 400-mL beaker with tap water and bring it to the hood. Place the salts, applicators, and tap water within easy reach on one side of the Bunsen burner.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Turn on the hand-held spectrophotometer and familiarize yourself with its components.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Create a new experiment and configure the spectrometer to measure emission intensity. Set the sample time to 200 ms and the number of readings at a given wavelength to 1. Record the settings and the experiment name in your lab notebooks.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Measure the spectrum of the room lights. Have one or two students hold the optical detector as close to the lights as possible without disconnecting the cables. Once ready, have a different student start the spectrometer. The spectrum should be clear, with minimal noise and no off-scale peaks. <strong>Note: </strong>If you have trouble, hold the probe in a nearly closed drawer or box to shield it from sunlight while pointing it at the room lights.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Immediately capture the spectrum when it looks good. Confirm that you have a high-quality spectrum before saving it. Record the wavelengths of the peaks in your data table.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Measure the emission spectra of the metal salts. Ignite the Bunsen burner and adjust the collar until the flame distinctly separates into an inner and outer flame.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Bring the spectrometer to the hood and arrange the cables so that the detector can be held about one inch from the flame.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Have one student prepare the spectrometer for the run. This student should have a clear view of the burner so they can begin acquiring data as soon as the salt enters the flame. Then, have another student hold the detector no closer than one inch from the flame. <strong>Note: </strong>Any closer risks damaging the detector. But you won&#39;t get a clear spectrum if the detector is too far away.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Have a different student take one of the applicators from the beaker of water and dip it into the tube of NaCl to coat the wet cotton with the salt. Then, carefully insert the salt-coated applicator about 1 mm into the outer flame, which will change color.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Start the spectrometer when the applicator enters the flame.<strong> Note: </strong>If the peak intensities are off-scale, adjust the detector position until all peaks are within detection limits. If the flame color change is hard to see, pick up more salt on the same applicator and try again until you see an intense color. If the spectrum is noisy or weak, try pointing the detector at a different part of the flame.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">When you see a good spectrum, capture and save it. Everyone should review the spectrum to ensure that it is of good quality. Write down the emission wavelengths in your table.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Submerge the NaCl applicator in your wastewater beaker. Always use a different applicator for each salt.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Follow the same procedure to test the remaining five salts, being careful to avoid cross-contamination between the salts. Once you have tested the last salt and recorded the wavelengths, set up data collection for the sparkler.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">At the instructor&#39;s hood, light the sparkler with the Bunsen burner and place it handle down in the Erlenmeyer flask. Remember, the sparks may be very hot. Turn off the gas to extinguish the Bunsen burner.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">As one student holds the detector close to the sparkler, have another student start data collection. Position the detector to get as many peaks in scale as possible without losing the less intense peaks.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Capture and save the spectrum once it looks good. Remember to write down the wavelengths in your table. <strong>Note: </strong>If the sparkler is long-lived, collect a second spectrum and either choose the best one or keep them both for the analysis.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Let the sparkler burn out in the hood while you send the collected data to everyone in the group and shut down the data acquisition system.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Bring the copper, barium, and strontium tubes to the waste hood and thoroughly rinse the tubes with deionized water into the designated waste container.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Flush the sodium, potassium, and lithium salts down the drain and rinse the remaining test tubes. Put away the test tubes and the other equipment.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Once the ashes and sparkler handle have cooled, dump them in the trash.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">First, plot the data for each run with intensity on the y-axis and wavelength on the x-axis.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Compare the sparkler spectrum to the background spectrum from the room lights. Identify which small peaks may be from the room lights.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Compare the metal spectra to the sparkler spectrum. Sodium appears to be the source of the peak at about 589 nm. There are no peaks matching the lithium spectrum, but potassium matches the large peak at 770 nm.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">The sparkler spectrum doesn&#39;t seem to have strontium peaks. However, barium is a good match for several peaks in the sparkler spectrum. Lastly, no copper seems to be present in the sparkler. Thus, we conclude that the sparkler was burning sodium, potassium, and barium when the spectrum was acquired.</div>
		</li>
	</ul>
	</li>
</ol>

Emisión de llamas metálicas

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Metal Flame Emission TestingExpand
	In this lab, you will excite the electrons of six metal ...

Balmer Series

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Spectral Emission Lines of Hydrogen, Helium, and Neon<button class="expand">Expand</button>
	<p>In this experiment, you will use a spectrophotometer to measure the distinct wavelengths of light emitted in the UV and visible range by electron relaxation in hydrogen, helium, and neon. Before starting the lab, make a table in your lab notebook for the elements that you will analyze, the color of the light that you observe from the lamps, and the recorded wavelengths.</p>
	<h4><strong>Table 1: Emission Wavelengths</strong></h4>
	<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
		<tbody>
			<tr>
				<td style="text-align: center;"><strong>Elements</strong></td>
				<td style="text-align: center;"><strong>Color</strong></td>
				<td style="text-align: center;"><strong>Distinct wavelengths, &#955; (nm)</strong></td>
			</tr>
			<tr>
				<td style="text-align: center;">H</td>
				<td style="text-align: center;"></td>
				<td style="text-align: center;"></td>
			</tr>
			<tr>
				<td style="text-align: center;">He</td>
				<td style="text-align: center;"></td>
				<td style="text-align: center;"></td>
			</tr>
			<tr>
				<td style="text-align: center;">Ne</td>
				<td style="text-align: center;"></td>
				<td style="text-align: center;"></td>
			</tr>
		</tbody>
	</table>
	<p><a href="https://www.jove.com/CDNSource/lm/labs/54/Table_1._Emission_wavelengths.xlsx" target="_blank">Click Here to download Table 1</a></p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">First, put on a lab coat, safety glasses, and nitrile gloves. We suggest students work in pairs for this experiment.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Turn on a hand-held spectrophotometer and create a new file for the hydrogen emission spectrum. Configure the spectrophotometer to measure emission intensity with a sampling time of 200 ms, with no sample averaging.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">When the instructor calls you, bring the spectrophotometer to the hydrogen lamp. The student holding the sensor should move close to the lamp, and the other should be ready to start the spectrophotometer acquisition.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">When the instructor turns on the lamp, hold the sensor at the center of the lamp and start displaying the spectrum. <strong>Note: </strong>Capture the spectrum as soon as it is clear and has minimal noise, as the lamp cannot be left on for more than 30 s at a time.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Save the hydrogen spectrum. Set up another experiment using the same parameters and acquire the spectrum for helium. Acquire a spectrum of neon in the same way.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Export your saved data, turn off the spectrophotometer, and put it away.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Set up the Rydberg formula to calculate the wavelengths of the Balmer series. <strong>Note:</strong> n<sub>initial</sub> is the number of the energy level where the excited electron starts, and n<sub>final</sub> is the energy level to which the electron relaxes. Set n<sub>final</sub> to 2.
		<h4><strong>Table 2: Frequency and Energy for Each Wavelength</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Rydberg constant (m<sup>-1</sup>) </strong></td>
					<td style="text-align: center;">1.098 &#215; 10<sup>7</sup></td>
				</tr>
				<tr>
					<td><strong>c (m/s)</strong></td>
					<td style="text-align: center;">2.998 &#215; 10<sup>8</sup></td>
				</tr>
				<tr>
					<td><strong>h (J&#183;s)</strong></td>
					<td style="text-align: center;">6.626 &#215; 10<sup>-34</sup></td>
				</tr>
				<tr>
					<td style="text-align: center;"><strong>ni &#8594; nf</strong></td>
					<td style="text-align: center;"><strong>&#955;<sub>calculated </sub>(nm) </strong></td>
					<td style="text-align: center;"><strong>&#955;<sub>measured</sub> (nm) </strong></td>
					<td style="text-align: center;"><strong>v (THz) </strong></td>
					<td style="text-align: center;"><strong>E (eV) </strong></td>
				</tr>
				<tr>
					<td style="text-align: center;">7 &#8594; 2</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">6 &#8594; 2</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">5 &#8594; 2</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">4 &#8594; 2</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">3 &#8594; 2</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/54/Table_2._Frequency_and_energy_for_each_wavelength.xlsx" target="_blank">Click Here to download Table 2</a></div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Find the wavelength of light emitted by an electron relaxing from level 3 to level 2. Fill in the Rydberg constant for R<sub>H</sub> and solve for 1/&#955;. <strong>Note:</strong> The reciprocal of this value is the wavelength, which can be converted to nm.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Calculate the transitions from energy levels 4, 5, 6, and 7 in the same way. <strong>Note: </strong>You should see a good match between your data and your calculations.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">For each wavelength, calculate the frequency in THz and the energy in eV using the following equations, where c is the speed of light and h is Planck&#39;s constant.
		<ul>
			<li><img src="https://www.jove.com/CDNSource/lm/labs/54/54_Procedure_1.jpg" /></li>
			<li><img src="https://www.jove.com/CDNSource/lm/labs/54/54_Procedure_2.jpg" /></li>
		</ul>
		</div>
		</li>
	</ul>
	<p>Look at the calculated energies. You should see a trend of the energy gap increasing by less with each added energy level. This is reflected in the spacing of the peaks in the hydrogen emission spectrum. Helium and neon share this energy level spacing trend.</p>
	<p>From the helium spectrum, adding even one more electron makes the spectral series harder to calculate and identify. This is even more apparent in neon, which has eight more electrons than helium.</p>
	</li>
</ol>

The Hydrogen Atom: Bohr Model and Balmer Series - Procedure

Serie Balmer

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Spectral Emission Lines of Hydrogen, Helium, and NeonExpand
	In this experiment, you will use a ...

Temperature Dependence

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Temperature Dependent Decomposition of Hydrogen Peroxide<button class="expand">Expand</button>
	<p><em>We suggest that students work in pairs for this experiment. Equipment controls may vary.</em></p>
	<p>In this lab, you&#39;ll perform a decomposition reaction where a single compound breaks down into two or more simpler products. You will observe the decomposition of hydrogen peroxide into water and oxygen. This decomposition happens very slowly, so you will use iron (III) nitrate as a catalyst to lower the activation energy.</p>
	<p>During this process, iron undergoes a redox reaction and then returns to its starting oxidation state. You will be able to see this as a color change in your solution during the reaction. You&#39;ll perform the same reaction at four different temperatures and track the rate of the reaction by recording the pressure inside the flask. This way you can measure how quickly oxygen was produced in each experiment. You&#39;ll use this to calculate the reaction&#39;s activation energy.</p>
	<p><strong>Table 1. Estimate the apparent activation energy for the decompostion of hydrogen peroxide</strong></p>
	<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
		<tbody>
			<tr>
				<td><strong>Trial&#160;</strong></td>
				<td><strong>Temperature (&#8451;)</strong></td>
				<td><strong>&#916;P (kPa/s)</strong></td>
				<td><strong>1/T&#160;</strong></td>
				<td><strong>ln (&#916;P)</strong></td>
			</tr>
			<tr>
				<td>1</td>
				<td></td>
				<td></td>
				<td></td>
				<td></td>
			</tr>
			<tr>
				<td>2</td>
				<td></td>
				<td></td>
				<td></td>
				<td></td>
			</tr>
			<tr>
				<td>3</td>
				<td></td>
				<td></td>
				<td></td>
				<td></td>
			</tr>
			<tr>
				<td>4</td>
				<td></td>
				<td></td>
				<td></td>
				<td></td>
			</tr>
		</tbody>
	</table>
	<p><a href="/CDNSource/labs/51/Table_1._Estimate_the_apparent_activation_energy_of.xlsx" target="_blank">Click Here to download Table 1</a> &#160;</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-1">
		<div class="lab-step">Before starting this experiment, put on a lab coat, safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-2">
		<div class="lab-step">Ensure that your hot plate is off and then place a 600-mL beaker on the hot plate.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Connect vacuum tubing to the barbed sidearm of a 125-mL B&#252;chner filter flask, and carefully clamp the filter flask in the 600-mL beaker so that the sidearm is just above the top of the beaker.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Fill a 400-mL beaker with deionized water., and pour the water into the 600-mL beaker until the water level is about 2&#8211;3 cm below the side arm.<br />
		<strong>NOTE</strong>: Make sure that the water is not able to get into the flask or vacuum line.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Immerse the thermometer in the water, clamping it in place so that the end is in contact with the outer wall of the flask. Ensure that you can read the current temperature, as well as the 40, 60, and 80 &#176;C marks.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Make sure that each hole of the 2-hole adapter is fitted with a tapered locking adapter. Check that all the adapters are firmly seated, since any air that escapes around them will affect your data.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Lock a 2-way stopcock into one of the stopper adapters. Then, lock one end of the flexible tubing into the second adapter with the other end into the connector of the gas pressure sensor.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Turn on the data acquisition device for the gas pressure sensor and ensure that the pressure is displayed in kPa.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Set the acquisition rate to two samples per second and the duration to 300 s. Then, display the pressure in real-time.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Label a 400-mL beaker as &#8216;waste&#8217;, a 50-mL beaker as &#8216;0.5 M Fe(NO<sub>3</sub>)<sub>3</sub>&#8217;, and a 100-mL beaker as &#8216;3% w/w hydrogen peroxide&#8217;.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Place a few paper towels on the work surface as a clean area for glassware that you will reuse. Keep a supply of paper towels on hand for later.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Then, bring the 50-mL and 100-mL beakers to the stock solution area. Pour about 30 mL of 0.5 M Fe(NO<sub>3</sub>)<sub>3</sub> in the 50-mL beaker and 100 mL of 3% w/w hydrogen peroxide in the 100-mL beaker.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Back at your workspace, setup a 20-mL volumetric pipette and fill it to the mark with 3% w/w hydrogen peroxide. Dispense the hydrogen peroxide into the filter flask and set the volumetric pipette aside.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Adjust the thermometer as needed so that it contacts the flask below the hydrogen peroxide solution level.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Fit the rubber stopper into the mouth of the filter flask, being careful not to loosen the connections to the sensor and the 2-way stopcock.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Check that the 2-way stop is closed. Open the vacuum line and monitor the pressure as it decreases. This will seal the stopper in the flask. Once the pressure reaches 10 kPa, close the vacuum.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Monitor the pressure for at least 1 min to confirm there are no slow leaks.<br />
		<strong>NOTE</strong>: If the pressure immediately starts rapidly increasing, there is a leak in your setup, so tighten the connections and try again until the pressure holds at 10 kPa when the vacuum line is closed.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Draw 5 mL of 0.5 M Fe(NO<sub>3</sub>)<sub>3</sub> into a 20-mL syringe. Expel all air from the syringe so that it only contains the solution.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Lock the syringe into the top of the 2-way stopcock. You are now ready to start the room temperature trial, so record the water temperature in your lab notebook.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Start acquiring gas pressure data. Allow the device to record data for about 15 s, then open the stopcock and quickly close it once all of the Fe(NO<sub>3</sub>)<sub>3</sub> has entered the flask. The observed increase in pressure is from the evolution of oxygen gas produced by the decomposition of hydrogen peroxide.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Once the data collection finishes, save your data. Then, disconnect the syringe and open the stopcock to vent the flask.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Take out the rubber stopper, carefully remove the thermometer from the clamp and the flask from the beaker, and disconnect the vacuum tubing from the filter flask.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Empty the flask into the waste beaker. Try not to get liquid in the side arm. Dry the outside of the flask with paper towels.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Rinse the interior of the flask with deionized water and pour the rinse into the waste beaker. If any liquid gets into the side arm, remove it with paper towels.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">Reconnect the flask to the vacuum line and clamp it in the 600-mL beaker in contact with the thermometer.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">Turn on the hotplate and heat the water around the flask until the thermometer reads 80 &#176;C. Then, turn off the heat.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Then, add 20 mL of 3% w/w hydrogen peroxide to the flask.</div>
		</li>
		<li data-sub-note-item="1-29">
		<div class="lab-step">Dry the stopper with paper towels. Do this after each trial to ensure that the stopper has a snug fit in the neck of the beaker and fit the stopper in the flask.</div>
		</li>
		<li data-sub-note-item="1-30">
		<div class="lab-step">Check that the stopcock is closed and evacuate the flask to about 10 kPa. Then, close the vacuum and confirm that there are no leaks.</div>
		</li>
		<li data-sub-note-item="1-31">
		<div class="lab-step">Draw 5 mL Fe(NO<sub>3</sub>)<sub>3</sub> solution into the syringe, expel the air from the syringe, and connect it to the stopcock.</div>
		</li>
		<li data-sub-note-item="1-32">
		<div class="lab-step">Record the temperature shown on the thermometer in your lab notebook, then, start collecting data.</div>
		</li>
		<li data-sub-note-item="1-33">
		<div class="lab-step">Wait about 15 s and introduce the Fe(NO<sub>3</sub>)<sub>3</sub> solution in the same way as before.<br />
		<strong>NOTE:</strong> As the pressure approaches 150 kPa, the stopper may pop off!</div>
		</li>
		<li data-sub-note-item="1-34">
		<div class="lab-step">After data collection finishes, save the data, vent and clean the filter flask, and set up for the third trial.</div>
		</li>
		<li data-sub-note-item="1-35">
		<div class="lab-step">Fill the 400-mL beaker with ice and add some to cool the water to about 60 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-36">
		<div class="lab-step">Perform the third trial in the same way as before. Remember to dry the stopper and the inside of the flask and to record the temperature prior to data collection.</div>
		</li>
		<li data-sub-note-item="1-37">
		<div class="lab-step">After the data is collected for that trial, cool the water to about 40 &#176;C and perform the fourth trial.</div>
		</li>
		<li data-sub-note-item="1-38">
		<div class="lab-step">Once you have finished all four trials, empty the filter flask and rinse it into the waste beaker one last time.</div>
		</li>
		<li data-sub-note-item="1-39">
		<div class="lab-step">Dispose of any excess 0.5 M Fe(NO<sub>3</sub>)<sub>3</sub> and the contents of the waste beaker in a container labeled for aqueous iron waste.</div>
		</li>
		<li data-sub-note-item="1-40">
		<div class="lab-step">Then, disassemble the apparatus and pour the leftover ice, water, and hydrogen peroxide in the sink. Wash your glassware following your lab&#39;s standard protocol.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="1" data-parent-collapse="">Results<button class="expand">Expand</button>
	<p>The decomposition of hydrogen peroxide with iron is a complex, multi-step process that we can&#39;t easily describe in a single equation. However, we can estimate the apparent activation energy from the rate of oxygen production and compare it to the apparent activation energy of the un-catalyzed process.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Find the rate of pressure change, which is directly proportional to the rate of oxygen production. For each experiment, make a plot of pressure with respect to time and find the point where the reaction started.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Identify the maximum pressure attained and determine the slope between the two points.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Once you&#39;ve determined the slopes and the corresponding temperatures in Kelvin for all of the temperatures, use the Arrhenius equation to estimate the apparent activation energy of this reaction.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Take the reciprocal of the temperatures in Kelvin and the natural log of the rate of change in pressure. Remember that the rate constant k is essentially equal to the change in pressure.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Make an Arrhenius plot and find the slope of the line.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">The slope is equal to the negative activation energy over the universal gas constant, so multiply the slope by the negative universal gas constant to get the apparent activation energy of the iron catalyzed decomposition reaction. You&#39;ll see a value in the range of 35&#8211;60 kJ/mol because the iron catalyst made the decomposition take less energy. The apparent activation energy of the uncatalyzed decomposition of hydrogen peroxide is around 78 &#8211; 88 kJ/mol.</div>
		</li>
	</ul>
	</li>
</ol>

Temperature Dependence and Arrhenius Equation - Procedure

Dependencia de la temperatura

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Temperature Dependent Decomposition of Hydrogen PeroxideExpand
	We suggest that students work ...

Electrolytic Cells

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Electrolytic Cells<button class="expand">Expand</button>
	<p>In this experiment, you will be assembling an electrolytic cell to perform electroplating. An electrolytic cell contains an anode and cathode connected by a power source, which drives the nonspontaneous redox reaction in the cell. When the anode material is oxidized, the ions travel to the cathode, where they are reduced and plated.</p>
	<p>In the case of this experiment, the electrolytic cell contains a copper anode and a brass key for the cathode. Oxidation of the anode creates copper(2+) ions, which are then reduced on the brass key, forming a thin plating of solid copper.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-3">
		<div class="lab-step">Put on gloves, safety goggles, and a lab apron, which must be worn at all times.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Obtain one 10-ohm resistor, one copper sheet electrode, one copper wire, and one piece of emery paper.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Use the emery paper to polish the brass key and the copper sheet. Rinse the key and the copper electrode with water. The brass key will be the cathode, and the copper sheet will be the anode.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Take one 50-mL beaker and a watch glass to the instructor&#39;s hood and obtain approximately 20 mL of acetone. Place the watch glass on top of the beaker to prevent evaporation and bring it back to your bench.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Label the other 50-mL beaker as &#39;organic waste&#39;.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Use a disposable pipette to rinse the copper electrode and key with acetone. Collect excess in the waste beaker. Place the key and copper electrode on a paper towel to dry.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Measure the initial masses of the key and copper electrode and record their values in your lab notebook.
		<h4><strong>Table 1: Moles of Cu Transferred</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td></td>
					<td style="text-align: center;"><strong>Mass of key (g) </strong></td>
					<td style="text-align: center;"><strong>Change in mass (g) </strong></td>
					<td style="text-align: center;"><strong>Moles Cu plated </strong></td>
					<td style="text-align: center;"><strong>Mass of Cu electrode (g) </strong></td>
					<td style="text-align: center;"><strong>Change in mass (g) </strong></td>
					<td style="text-align: center;"><strong>Moles Cu lost </strong></td>
				</tr>
				<tr>
					<td style="text-align: center;">0 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">5 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">1<sup>st</sup> 30 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">2<sup>nd</sup> 30 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/53/Table_1._Moles_of_Cu_Transferred.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Set up the electrolytic cell. Use one electrical wire with alligator clips to connect the negative terminal on the battery to the current probe. Wrap the 10-ohm resistor around the other end of the current probe.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Use another wire to connect the positive terminal on the battery to the copper electrode.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Wrap the copper wire around the brass key and use an electrical wire to connect the resistor on the current probe to the copper wire on the brass key.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Obtain about 200 mL of concentrated copper sulfate in a 250-mL beaker. The amount does not need to be exact. Bring the beaker back to your bench and set it on the stir plate. Carefully, place a magnetic stir bar in the beaker and turn the stir setting on to high.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Connect the data acquisition system to the current probe and allow the data acquisition system to sense the probe. It should return a reading in amps. Change the rate to two scans per min and the duration to 5 min.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Place the brass key in the beaker. Hang it off the side of the beaker so that the key is almost completely submerged but does not touch the magnetic stir bar. <strong>Note: </strong>The copper wire should not be in the solution.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Place the copper electrode in the beaker, bending it so that it hangs over the edge of the beaker. Ensure that it is not touching the stir bar or the brass key.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Start the scan and let it collect data for 5 min. This will act as a test run to make sure plating occurs on the brass key.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">After the scan ends, remove the key and copper electrode. The copper plating on the brass key should be evident. If it is not visible, check your circuit to make sure that the battery is connected in the correct orientation.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Once you have completed a successful 5-min plating, disconnect the key and copper electrode from the wiring. Remove the copper wire from the key and rinse the key and copper electrode with water and then acetone. Lay them on a paper towel to dry.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Measure the masses of the key and the copper electrode and record them in your lab notebook.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Reconnect the key and copper electrode and place them back in the solution like before. Restart the run on the data acquisition system, making sure that the rate is set to two scans per min. With the duration set to 30 min, allow the electroplating process to run.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">After the scan is complete, remove the electrode and key from the solution, disconnect them from the wires, and rinse them with water and then acetone. Allow them to dry on a paper towel, then weigh them and record their masses in your notebook.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Reassemble the setup and repeat the electroplating for a second 30-min trial. When the scan is complete, remove the key and copper electrode, rinse them like before, and record their mass.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Save the recorded data as a text file on a flash drive.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">To clean up, turn the stir setting off and remove the stir bar from the solution using forceps. Dispose of the acetone in the organic waste container provided by your instructor. The copper sulfate solution can be reused for future labs, so pour the concentrated copper sulfate back into the carboy.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">Rinse all of your glassware with water and return it to the instructor.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">First, calculate the total charge Q that flowed through the system during the different trials. One coulomb is the quantity of electricity flowing through a wire carrying 1 ampere of current in 1 s, thus Q = I x t.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Review the current probe data for the first 5-min electroplating trial.<strong> Note: </strong>If the current dropped to 0 or close to 0 at the end of the trial, then the electrons stopped flowing from the copper electrode to the key. Only use the values recorded before the drop in current occurred. If the current drop to 0 early in the plating process, repeat the trial.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">The current varies over time, so calculate the average current, I.
		<h4><strong>Table 2: Moles of Electrons Transferred</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td style="text-align: center;"><strong>Trial</strong></td>
					<td style="text-align: center;"><strong>Time (s) </strong></td>
					<td style="text-align: center;"><strong>Current<sub>average</sub> (A) </strong></td>
					<td style="text-align: center;"><strong>Total charge (C) </strong></td>
					<td style="text-align: center;"><strong>Moles (e?) </strong></td>
				</tr>
				<tr>
					<td style="text-align: center;">5 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">1<sup>st</sup> 30 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">2<sup>nd</sup> 30 min</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">Total</td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/53/Table_2._Moles_of_Electrons_Transferred.xlsx" target="_blank">Click Here to download Table 2</a></div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Use the average current over the total time to determine the total charge transferred during electroplating, Q. About 20 coulombs were transferred during the 5-min trial, and between 110 and 120 coulombs were transferred during each 30-min trial. The total charge transferred over the entire 65-min electroplating process was about 250 coulombs.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Use the total charge transferred to calculate the moles of electrons plated during each trial. The moles of electrons plated equals the total charge transferred divided by the Faraday constant. The Faraday constant represents the magnitude of electric charge per mole of electrons and is determined by multiplying the charge of an electron by Avogadro&#39;s constant.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Determine the moles of electrons that were transferred for the 5-min and 30-min trials.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">Calculate the moles of copper that were plated on the key after each trial. Similarly, determine the moles of copper lost from the copper sheet electrode.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Compare the moles of copper that were lost from the electrode to the amount that was plated to the brass key. The numbers should be close.</div>
		</li>
		<li data-sub-note-item="2-9">
		<div class="lab-step">Check to see if these values match what is expected based on the number of moles of electrons that were transferred. The reduction of 1 mole of copper(2+) ions requires 2 moles of electrons to produce 1 mole of solid copper.</div>
		</li>
	</ul>
	</li>
</ol>

Electrolytic Cells: Construction and Electroplating - Procedure

Celdas electrolíticas

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Electrolytic CellsExpand
	In this experiment, you will be assembling an electrolytic cell to ...

Basic Organic Chemistry Techniques

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Synthesis of Benzoic Acid<button class="expand">Expand</button>
	<p>In this lab, you&#39;ll learn several important techniques that you&#39;ll use throughout this class. This includes measuring the mass or volume of reactants and products, methods of heating and cooling reaction mixtures, proper selection and handling of glassware, and separating solids and liquids by vacuum filtration. First, you&#39;ll synthesize benzoic acid by protonating sodium benzoate with hydrochloric acid, or HCl, using water as the solvent. Sodium benzoate is very soluble in water, but benzoic acid is not, so you can filter the solid product out of the solution.</p>
	<p>You&#39;ll use vacuum filtration, which is used for powdery solids, to filter out the benzoic acid. Benzoic acid is less soluble in water at lower temperatures, so you&#39;ll collect more product if you cool the reaction solution before you filter it. When you do this lab, remember that HCl is toxic and a strong acid. It&#39;s always best to work with strong acids and organic solvents in a fume hood. If you spill any HCl, follow your lab&#39;s procedures for neutralizing and cleaning up strong acids.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-3">
		<div class="lab-step">Put on a lab coat, safety glasses, and nitrile gloves. Change your gloves if you get acid or organic solvent on them.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Bring a clean 50-mL beaker and your lab notebook to the balance, and then tare a clean empty weighing boat on the balance.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Use a clean spatula to measure out ~2 g of sodium benzoate.<strong> Note:</strong> Stay between 1.9 and 2.1 g.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Dispose of any extra sodium benzoate into the appropriate waste container. Close the bottle of sodium benzoate when you&#39;re done with it.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Write down the mass of sodium benzoate and pour it into your beaker. Clean the spatula with a lab wipe so that it can be used again and return to your fume hood.
		<h4><strong>Table 1: Reaction yield of benzoic acid</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td style="text-align: center;"><strong>Mass of sodium<br />
					benzoate (g)</strong></td>
					<td style="text-align: center;"><strong>Moles of sodium<br />
					benzoate</strong></td>
					<td style="text-align: center;"><strong>Volume of<br />
					HCl (mL)</strong></td>
					<td style="text-align: center;"><strong>Moles of<br />
					HCl</strong></td>
					<td style="text-align: center;"><strong>Moles of benzoic<br />
					acid</strong></td>
					<td style="text-align: center;"><strong>Mass of benzoic<br />
					acid (g)</strong></td>
				</tr>
				<tr>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td></td>
					<td></td>
					<td></td>
					<td></td>
					<td><strong>Theoretical yield</strong></td>
					<td></td>
				</tr>
				<tr>
					<td style="text-align: center;">-</td>
					<td style="text-align: center;">-</td>
					<td style="text-align: center;">-</td>
					<td style="text-align: center;">-</td>
					<td><strong>Percent yield</strong></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/56/Table_1._Reaction_yield_of_benzoic_acid.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Get a clean 10-mL graduated cylinder and measure 10 mL of deionized water. Pour the water into the beaker of sodium benzoate. Stir the solution with a glass rod until the sodium benzoate has completely dissolved.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Obtain a clean 5-mL graduated cylinder and measure 5 mL of 3 M HCl. <strong>Note: </strong>If you pour too much, use a Pasteur pipette to transfer the excess to a small beaker labeled &#8216;acid waste&#8217;. Close the bottle and put it back when you&#39;re done.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Use a clean Pasteur pipette to draw up a small amount of HCl from your graduated cylinder. Start adding the HCl to the sodium benzoate solution at a rate of about one drop every 6 seconds or 10 drops/min. Stir the solution frequently with the glass rod. This should take about 10 min. <strong>Note:</strong> As you add more HCl, you&#39;ll start to see benzoic acid precipitating from the solution.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">When you are done, fill a 600-mL beaker about halfway with crushed ice and add tap water to just fill the spaces between the ice to make an ice bath.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Place the ice bath by a lab stand in your fume hood and use a medium clamp to hold the reaction beaker in the bath. Make sure that the surface of the solution is below the ice.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Clamp a thermometer in the reaction solution.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">While the reaction cools, obtain 25 mL of deionized water in a 50-mL graduated cylinder. Place the graduated cylinder in a 600-mL beaker and pack ice around it to cool the water.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Once the reaction solution reaches 10 &#176;C, it&#39;s ready to be filtered. Set up another lab stand and obtain a clean 250-mL filter flask. Clamp the flask upright on the lab stand.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Ensure that your vacuum tubing is connected to the vacuum source, and then carefully push the free end of the tubing onto the barbed arm of the flask.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Place a rubber adapter and a B&#252;chner funnel in the mouth of the flask. Confirm that the reaction solution has reached 10 &#176;C and remove the thermometer from the beaker.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Obtain a piece of circular filter paper and place it in the B&#252;chner funnel so that the small holes are completely covered.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Get a new Pasteur pipette, and use a few drops of cold deionized water to wet the filter paper. <strong>Note: </strong>This helps keep the filter paper in place when you pour the solution into the funnel.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Open the vacuum line part way to reduce the pressure in the flask.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Remove the beaker from the ice bath, stir the solution well with the glass rod until the solid is swirling around in the liquid, and then slowly pour it onto the filter paper. <strong>Note:</strong> If the liquid does not move quickly through the funnel, make sure that there are no gaps between the funnel, adapter, and flask, and then gradually open the vacuum until the liquid rapidly flows into the flask.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Use a clean Pasteur pipette to rinse the inner walls of the beaker with ~10 mL of cold deionized water and pour the rinse into the funnel. Pour the rest of the cold deionized water over the benzoic acid on the filter to wash it. <strong>Note:</strong> This is an important step that removes impurities, side products, and unreacted compounds.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Leave the benzoic acid in the funnel with the vacuum running until it is completely dry. <strong>Note: </strong>This usually takes ~2 h, so let&#39;s continue to the second half of the lab in the meantime.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Refluxing Tetrahydrofuran (THF) and Measuring Product Mass<button class="expand">Expand</button>
	<p>While your benzoic acid dries, you&#39;ll practice refluxing tetrahydrofuran, or THF, which has a boiling point of 66 &#176;C. THF is volatile, flammable, and an irritant, so avoid letting it touch your skin and always work with it in a fume hood. Refluxing is a technique that constantly condenses the vapor and returns it to the flask. This allows reactions to be performed at high temperatures, such as at the solvent&#39;s boiling point, without losing the solvent to evaporation.</p>
	<p>Refluxing is achieved with a special piece of glassware called a condenser, which is attached directly to your flask. The condenser is cooled with water flowing through the outer chamber. As vapor rises through the condenser, it loses heat to the cool walls, condenses, and drips back into the flask.</p>
	<p>Refluxing is usually performed in a round-bottom flask. These flasks must be heated in a heating bath or with specialized equipment, but they provide more even heating than an Erlenmeyer flask or beaker as a result. Water baths are typically used for experiments performed below 80 &#8211; 100 &#176;C.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-4">
		<div class="lab-step">Set up the glassware and equipment for reflux. Place a lab jack by your available lab stand and set a stirring hotplate on top of it. Clamp a 50-mL round-bottom flask at least 12 cm above the hotplate.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Bring a 50-mL graduated cylinder to the solvent hood and measure 25 mL of THF. If you pour too much, label a small beaker &#8216;organic waste&#8217; and pipette the excess into that. Remember to cap the bottle when you&#39;re done.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Carefully pour the THF into the round-bottom flask, clean up any spills with a lab wipe or paper towel, and add a small oblong stir bar to the flask.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">Position a medium clamp ~20 cm above the flask. Obtain a condenser and apply vacuum grease to the lower ground-glass joint.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Fit the condenser into the flask and rotate them in opposite directions until the vacuum grease is evenly spread between the two ground-glass surfaces.</div>
		</li>
		<li data-sub-note-item="2-9">
		<div class="lab-step">Clamp the condenser in place and use a lab wipe to remove excess grease from the connection between the two pieces of glassware.</div>
		</li>
		<li data-sub-note-item="2-10">
		<div class="lab-step">Attach rubber tubing to each of the ports on the condenser. Place the free end of the tubing connected to the top port, which is the outlet, in the drain. Connect the free end of the tubing from the bottom port, which is the inlet, to the waterline.</div>
		</li>
		<li data-sub-note-item="2-11">
		<div class="lab-step">Fill a 250-mL beaker with ~200 mL of tap water and place this water bath on the hotplate. Use the lab jack to raise the bath until the water level is about 2/3 of the way up the spherical part of the flask. This will ensure the THF heats evenly.</div>
		</li>
		<li data-sub-note-item="2-12">
		<div class="lab-step">Secure a thermometer (range 0 &#8211; 100 &#176;C) in the bath using the thermometer clamp.</div>
		</li>
		<li data-sub-note-item="2-13">
		<div class="lab-step">Slowly open the water tap, watch the condenser for leaks as it fills, and confirm that the water is flowing into the drain.</div>
		</li>
		<li data-sub-note-item="2-14">
		<div class="lab-step">Slowly turn up the magnetic stirrer until the THF is stirring well. If the stir bar bounces around, turn down the stir motor and try again more slowly.</div>
		</li>
		<li data-sub-note-item="2-15">
		<div class="lab-step">Start heating the water bath to about 70 &#176;C until the THF starts to boil. <strong>Note: </strong>You&#39;ll see vapor condensing in the lower part of the condenser).</div>
		</li>
		<li data-sub-note-item="2-16">
		<div class="lab-step">Monitor the refluxing THF for 10 min. <strong>Note:</strong> Turn down the heat if the bath goes above 70 &#176;C or if vapor leaves the condenser.</div>
		</li>
		<li data-sub-note-item="2-17">
		<div class="lab-step">After 10 min, remove the thermometer and turn off the heat and the stir motor. Carefully lower the lab jack until the flask is clear of the water bath. Wait at least 10 more min for the setup to cool, then unplug and remove the hotplate.</div>
		</li>
		<li data-sub-note-item="2-18">
		<div class="lab-step">Turn off the water tap, unclamp the condenser, and carefully detach it from the flask. Tilt the condenser until most of the water has flowed through the outlet tubing into the drain. Then, disconnect the inlet tubing from the condenser and let the remaining water flow into the drain. Do the same for the outlet tubing.</div>
		</li>
		<li data-sub-note-item="2-19">
		<div class="lab-step">Use lab wipes to remove the vacuum grease from the condenser and the flask, then retrieve the stir bar from the flask.</div>
		</li>
		<li data-sub-note-item="2-20">
		<div class="lab-step">Bring the flask to the waste hood and empty it into the non-halogenated organic waste container. Pour any excess HCl or THF into the acid and organic wastes, respectively. Empty the ice and water baths into the sink and rinse the beakers with tap water.</div>
		</li>
		<li data-sub-note-item="2-21">
		<div class="lab-step">Clean most of your other glassware while the benzoic acid from earlier finishes drying according to your lab&#8217;s standard practices. Usually, you&#39;ll rinse your glassware both with an organic solvent, like acetone, and with detergent and deionized water. <strong>Note:</strong> Your lab may have specific procedures for glassware used with acids. If so, follow that procedure to clean the graduated cylinder used with HCl and your acid waste beaker, if applicable.</div>
		</li>
		<li data-sub-note-item="2-22">
		<div class="lab-step">Remove the reusable pipette bulbs and dispose of your pipettes in the glass waste container. Throw out used lab wipes and paper towels in the lab trash.</div>
		</li>
		<li data-sub-note-item="2-23">
		<div class="lab-step">Check on your benzoic acid. If it is dry, turn off the vacuum and break the vacuum seal by disconnecting the tubing from the filter flask. Gently place the funnel in it 250-mL beaker and bring it and your lab notebook to the balance.</div>
		</li>
		<li data-sub-note-item="2-24">
		<div class="lab-step">Tare a weighing boat and use a clean spatula to transfer the product to the weighing boat. Record the mass of your product in your lab notebook.</div>
		</li>
		<li data-sub-note-item="2-25">
		<div class="lab-step">Then, put the product in the lab trash and wipe off the spatula. Dispose of the filtrate in the aqueous waste container.</div>
		</li>
		<li data-sub-note-item="2-26">
		<div class="lab-step">Clean the rest of your glassware, throw out the filter paper and other waste in the lab trash, and put away your lab equipment. Lastly, clean the floor of your fume hood with a damp paper towel.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="3" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="3-1">
		<div class="lab-step">Calculate the reaction yield for the protonation of sodium benzoate. Identify the reagent that the reaction runs out of first, which is called the limiting reagent.</div>
		</li>
		<li data-sub-note-item="3-2">
		<div class="lab-step">Calculate the number of moles of sodium benzoate and HCl that you used. <strong>Note:</strong> You used about 0.014 moles of sodium benzoate and 0.015 moles of HCl. Thus, the maximum yield of benzoic acid is equal to the starting amount of sodium benzoate in moles.</div>
		</li>
		<li data-sub-note-item="3-3">
		<div class="lab-step">Convert the mass of your benzoic acid to moles, divide that by the moles of sodium benzoate that you used, and multiply it by 100 to get the percent yield. <strong>Note:</strong> The recovered yield for this reaction is usually between 80% and 98% because a small amount of benzoic acid stays in solution. If the yield is above 100%, then it&#39;s likely that your product was still wet when you weighed it. Impurities, unreacted compounds, and products of side reactions can also affect the accuracy of yield calculations.</div>
		</li>
	</ul>
	</li>
</ol>

Técnicas Básicas de Química Orgánica

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Synthesis of Benzoic AcidExpand
	In this lab, you&#39;ll ...

Melting Points

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Determining the Melting Points of Naphthalene, Urea, and an Unknown Mixture<button class="expand">Expand</button>
	<p>In this experiment, you will measure the melting point range of two known substances, naphthalene and urea, by observing the melting phenomenon during heating. You&#39;ll then analyze a mixture of urea and an unknown substance to observe how the unknown impurity affects the melting point range.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Put on a lab coat, splash-proof safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Weigh ~1 mg of naphthalene using the analytical balance, and carefully, bring it back to your bench.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Transfer the naphthalene onto a watch glass, and then crush it using the metal spatula until it becomes a fine powder.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Carefully pick up one capillary tube and tap the open end on the powder to force some of the solid into the tube.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Obtain a long glass tube from the common bench and hold it upright over your bench. Pick up the capillary with the open end upward and then drop it through the glass tube. Allow the capillary to bounce off the benchtop to pack the solid at the bottom.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Retrieve the capillary and tap its open end on the naphthalene powder again to force more of it into the capillary. Continue loading naphthalene into the capillary and dropping it through the glass tube until 1 &#8211; 2 mL of powder is packed at the bottom of the capillary.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Use a rubber band to attach the capillary to a digital thermometer, with the bottom of the capillary just above the bottom of the thermometer. <strong>Note:</strong> Make sure that the rubber band is at least 8 &#8211; 9 cm above the solid in the capillary.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Set up a stirring hotplate and a lab stand in a fume hood and clamp the thermometer above the hotplate.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Place the provided mineral oil bath on the hotplate and add a magnetic stir bar. Start stirring the bath at a moderate speed over low heat.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Lower the thermometer and capillary setup into the oil bath until the sample is about 5 cm deep in the bath. <strong>Note:</strong> Make sure that the rubber band is above the mineral oil.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Increase the hotplate temperature to 60&#176;C, which is about 20&#176; below the melting point of naphthalene in the literature.<strong> Note:</strong> It will take about 10 min for the entire oil bath to reach the same temperature as the hotplate.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Once the bath reaches 60&#176;C, heat it to 75&#176;C at a rate of 5&#176;C/min. When the bath is close to the melting point of naphthalene (80&#176;C), heat the bath by 1 &#8211; 2 &#176;C/min while carefully observing the solid in the capillary.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">At the first drop of liquid in the capillary, record the temperature of the oil bath. Keep watching the capillary tube as you slowly increase the temperature. Record the temperature when the last piece of solid melts.
		<h4><strong>Table 1: Melting Points of Naphthalene, Urea, and an Unknown Mixture</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td></td>
					<td colspan="2" style="text-align: center;"><strong>Melting point temperature (&#176;C)</strong></td>
				</tr>
				<tr>
					<td><strong>Substance</strong></td>
					<td style="text-align: center;"><strong>Start</strong></td>
					<td style="text-align: center;"><strong>End</strong></td>
				</tr>
				<tr>
					<td>Napthalene</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea + Unknown (trial 1)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea + Unknown (trial 2)</td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/66/Table_1._Melting_points_of_naphthalene,_urea,_and_an_unknown_mixture.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Carefully remove the capillary and thermometer from the oil bath and set them aside to cool.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Weigh roughly 1 mg of urea and transfer it to a clean watch glass. Crush the urea to a powder. Load the powder into a capillary tube as before.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Attach the capillary to the thermometer with the rubber band. Heat the oil bath to 110&#176;C, which is about 20&#176; below the reported melting point of 132&#176;C for urea.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Insert the thermometer and capillary tube into the oil bath. Heat the bath to about 125&#176;C at 5&#176;C/min while watching the capillary.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">When the bath reaches 125&#176;C, heat the bath by 1 &#8211; 2&#176;C /min. Record the temperature when the first drop of liquid appears and when the last bit of solid melts.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Turn off the hotplate and remove the capillary and thermometer from the oil bath to allow them to cool.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Test the sample of urea mixed with an unknown impurity, which was prepared by your instructor. Perform two runs of this sample, so weigh 2 mg of the sample on the balance and transfer it to a watch glass.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Crush the sample to powder and load two capillaries by tapping them on the powder and dropping them through the glass tube like before.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Once the oil bath has cooled to at least 80&#176;C, turn on the stir motor and set the hotplate to 80&#176;C. Attach one of the loaded capillaries to the thermometer and clamp them in the oil bath.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">In the first test run, increase the temperature by 10&#176;C/min until the sample has melted to determine the rough melting point range. Record the temperature when you see the first drop of liquid form and the last drop of liquid form to determine the rough melting point range.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Turn off the hotplate and allow it to cool. Once the oil bath has cooled to at least 80&#176;C, attach the second sample to the thermometer and clamp them in the bath. Turn the stir motor back on and set the hotplate to 80&#176;C.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">For the second test, heat the bath by 5&#176;C/min until you are close to the rough melting point range, and then continue heating by 1 &#8211; 2&#176;C/min to accurately capture the melting point range.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">When you have finished measuring the melting point of the urea mixed with the unknown substance, turn off the hotplate and detach the capillary tube from the thermometer. Dispose of your capillary tubes in the glass waste container.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Return the mineral oil to your instructor, and clean all of your glassware using detergent and water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">First, look at the melting point range of naphthalene. These differences may be caused by experimental errors, such as heating the sample too quickly, or by impurities in the sample.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Next, check the results for the pure urea sample. Why is urea&#39;s melting point so much higher than naphthalene&#39;s? Looking at the structure of naphthalene, the intermolecular forces must be primarily London dispersion forces. Urea is capable of hydrogen bonding, so the intermolecular forces in solid urea are much stronger than the forces in solid naphthalene.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Finally, look at the results from the urea sample with the impurity. The melting point range should be broader and lower than the range for pure urea because of freezing point depression. As expected, the melting point range obtained was 127 &#8211; 130&#176;C, which is lower than the range for pure urea.</div>
		</li>
	</ul>
	</li>
</ol>

Determination of Melting Points - Procedure

Puntos de fusión

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Determining the Melting Points of Naphthalene, Urea, and ...

Boiling Points

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Boiling point determination of acetone and ethanol<button class="expand">Expand</button>
	<p>The temperature at which a pure organic substance changes from the liquid phase to the gas phase is known as the boiling point. A liquid&#39;s boiling point can be determined using the capillary method, where an inverted capillary is placed in the liquid of interest and the liquid is heated. As the temperature increases, the air in the capillary escapes and is replaced by the vapor of the liquid. The vapor pressure in the capillary increases with temperature. Once it exceeds the atmospheric pressure, the vapor escapes the capillary in a stream of bubbles. When the heat is removed, the liquid cools, and the vapor pressure in the capillary decreases. When the vapor pressure reaches the atmospheric pressure, the liquid begins to fill the capillary. The temperature at which this occurs is the boiling point.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Put on a lab coat, splash-proof safety glasses, and nitrile gloves. This experiment must be conducted in a hood.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Attach a small test tube to the thermometer using a rubber band, and secure the thermometer in the clamp.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Obtain acetone and bring it back to your hood. Using your glass pipette and a bulb, measure 1 mL of acetone and transfer it into the small test tube.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Align the thermometer end so that it is level with the acetone in the test tube, keeping them close to each other. Invert a capillary tube and place it in the test tube so that the open end is facing downwards.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Use a 250-mL beaker to create a water bath. Add approximately 180 mL of water to the beaker, and place it on the hotplate.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Lower the thermometer and test tube into the water bath. Turn on the hotplate to the lowest setting, about 30&#176;C.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Slowly increase the temperature on the hotplate by 10 &#8211; 20&#176;C every 10 min, and closely observe the liquid in the test tube. When you start to see occasional bubbles in the liquid, increase the heat setting by only 5&#176;C every 10 min.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Closely observe the capillary tube inside the test tube. Report the temperature at which a rapid and continuous stream of bubbles comes out of the capillary.
		<h4><strong>Table 1: Boiling point of acetone and ethanol</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td></td>
					<td colspan="2" style="text-align: center;"><strong>Boiling point temperature (&#176;C)</strong></td>
				</tr>
				<tr>
					<td></td>
					<td style="text-align: center;"><strong>Bubbles </strong></td>
					<td style="text-align: center;"><strong>Liquid in capillary </strong></td>
				</tr>
				<tr>
					<td>Acetone</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Ethanol</td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/57/Table_1._Boiling_point_of_acetone_and_ethanol.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Turn off the heat and allow the water bath to cool. Keep observing the capillary as the production of bubbles decreases until no bubbles emerge from the capillary. The liquid will start to rise in the capillary. Record the temperature at which this occurs.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Label a clean 25-mL beaker as &#8216;organic waste&#8217;. Once the water bath has cooled to about 35&#176;C, remove the thermometer and test tube from the bath. Detach the test tube from the thermometer and pour the acetone into the waste beaker.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Use a clean test tube and capillary and repeat the experiment using 1 mL of ethanol.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">After you have measured the boiling point of ethanol, allow the water bath to cool. Once it has cooled sufficiently, remove the test tube and thermometer from the water bath, detach the test tube from the thermometer, and pour the ethanol into the organic waste beaker.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Dispose of the water from the water bath down the sink and place the capillaries and test tubes in the glass disposal. Dispose of the organic waste in the container provided by your instructor.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Wash all of your glassware with detergent and water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<p>In this experiment, we measured the boiling point of acetone to be 56&#176;C, which compares well to the reported value. Similarly, the boiling point of ethanol was measured to be 78&#176;C. Errors in the boiling point measurement can be attributed to many experimental errors, such as heating the water bath too rapidly, or poor alignment of the thermometer and sample.</p>
	<p>The boiling point of an organic substance is directly related to its structure, where stronger intramolecular forces result in a higher boiling point as molecules are able to hold onto each other and remain in the liquid phase longer. The higher boiling point for ethanol is observed due to the OH structure that causes hydrogen bonding between the molecules. Acetone has a polar CO double bond, which results in dipole-dipole forces. Since hydrogen bonding is stronger than dipole-dipole forces, ethanol has a higher boiling point.</p>
	<p>Additionally, ethanol has a lower molecular weight than acetone. However, molecular weight has less of an impact on the boiling point than the molecular structure. For example, butane is a gas at room temperature and pressure, as it has a boiling point lower than 25&#176;C. Ethanol has a slightly lower molecular mass than butane, but it is liquid at room temperature and, therefore, has a boiling point higher than room temperature. This is due to the hydrogen bonding between the ethanol molecules, which is stronger than the van der Waals forces between the butane molecules.</p>
	<ul class="lab-items">
	</ul>
	</li>
</ol>

Determination of Boiling Points by Capillary Method - Procedure

Puntos de ebullición

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Boiling point determination of acetone and ethanolExpand
	...

Recrystallization

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Recrystallization of Acetanilide<button class="expand">Expand</button>
	<p>In this part of the lab, you&#39;ll purify acetanilide by recrystallization from an aqueous solution. Acetanilide is moderately soluble in boiling water, but it&#39;s much less soluble in room temperature and cold water. Aniline, a potential impurity, is much more soluble in room temperature water. Thus, you&#39;ll first make a saturated solution of acetanilide in boiling water. Then, you&#39;ll slowly cool the solution to room temperature.</p>
	<p>As the acetanilide&#39;s solubility decreases, it will slowly form flat colorless or white crystals. Water-soluble impurities will remain in solution. You will then cool the solution to further decrease the solubility of acetanilide. Finally, you&#39;ll recover the crystals with vacuum filtration and measure the melting point of your crystals.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-3">
		<div class="lab-step">Before you start the lab, put on a lab coat, safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">To begin, bring a 125-mL Erlenmeyer flask and your lab notebook to the analytical balance to obtain your acetanilide.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Measure 2 g of acetanilide in a tared weighing boat and record the precise mass in your lab notebook. Add the acetanilide to the flask and bring it back to your fume hood.
		<h4><strong>Table 1: Recrystallization of acetanilide</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Compound</strong></td>
					<td><strong>Mass (g) </strong></td>
					<td><strong>Melting point (&#176;C) </strong></td>
				</tr>
				<tr>
					<td>Acetanilide</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Seed crystal (if used)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Recrystallized acetanilide<br />
					(<em>subtract seed crystal if used</em>)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td><strong>Percent recovery</strong></td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/58/Table_1._Recrystallization_of_acetanilide.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Then, measure 30 mL of deionized water and carefully pour it into the flask of acetanilide.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Place the flask on a stirring hotplate, add a stir bar, and set the hotplate to medium heat and stirring. Let the mixture boil for 4 &#8211; 5 min to dissolve the acetanilide.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">If you see solid acetanilide after the solution has boiled for 5 min, measure another 10 mL of deionized water. Use a Pasteur pipette to add water dropwise until either the solid dissolves or you&#39;ve added all 10 mL.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Let the solution boil for at least a minute after each milliliter before adding more water.<strong> Note:</strong> It&#39;s important to add water slowly so that you don&#39;t cool the solution too much or add more water than you need.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">If you still see some solid after that, those are impurities that you must remove by hot filtration. If you do not see solid, continue the lab at step 14.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">To perform hot filtration, place about 15 mL of deionized water and one or two boiling chips in a 50-mL beaker and start heating it on a hotplate.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Clamp another 125-mL Erlenmeyer flask on a hotplate and place a wide stem or stemless glass funnel in the flask. Fold a large piece of circular filter paper in quarters, place it point down in the funnel, and open it into a cone.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Once the water boils, use a pipette to wet the filter paper with hot water. Then, use tongs to pick up the flask of acetanilide solution and pour the hot liquid into the funnel, being careful not to let it overflow. <strong>Note:</strong> If the stir bar falls into the funnel, retrieve it with tweezers and rinse it with hot water.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Then, rinse the inside of the first flask with a few milliliters of hot water, pour the contents into the funnel, and dissolve any crystals that form with hot water.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Once the funnel is empty, use tongs to move it to the first flask. Carefully unclamp the second flask. You can now continue with the lab as usual.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Once there is no visible solid in your hot acetanilide solution, turn off the heat and stir motor and use tongs to place the flask on the floor of the hood.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Leave the solution undisturbed as it cools to room temperature, which usually takes at least 15 min. Moving or shaking the flask will make it harder for crystals to form.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">While you wait, place a small amount of the starting acetanilide material in a weighing boat and bring it to the melting point apparatus.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Pack a capillary tube with the acetanilide and measure and record its melting point.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Once the solution cools, look for crystals without moving the flask too much. If you don&#39;t see any, use a glass rod to gently scratch the inside of the flask under the solution. It&#39;s easier for crystals to start to form on scratched or rough surfaces.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">If crystals still haven&#39;t formed after 10 more min, ask your instructor for a seed crystal of high purity acetanilide. Measure and record the mass of the seed crystal, and then drop it into the room temperature acetanilide solution. Crystal growth will then occur on the seed crystal.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Once you see several crystals in the flask, prepare two ice baths in 600-mL beakers. One ice bath should nearly fill the beaker, and the other should occupy about half of the beaker.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Measure 5 mL of deionized water and place it in the full ice bath. Confirm that the flask is cool to the touch and that several crystals have formed before gently placing it in the half-full ice bath. Leave the flask undisturbed to improve crystal growth.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Check the crystal growth progress every 15 min. Once it looks like most of your acetanilide has crystallized, or you don&#39;t see much crystal growth over a 15-min period, set up for a vacuum filtration using a 125- or 250-mL filter flask.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Wet the filter paper with 1 mL of ice-cold water. Then, start the vacuum and pour the contents of the flask into the B&#252;chner funnel of the vacuum filtration setup.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">Scrape crystals from the flask into the funnel using a glass rod or flexible spatula and rinse the remaining crystals into the funnel with about 1 mL of cold deionized water.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">Then, stop the vacuum, break the seal, and pour the rest of the cold deionized water into the funnel. Gently stir the crystals with the glass rod for a few seconds to wash them, being careful not to tear the filter paper.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Turn on the vacuum to drain the funnel. Then, stop the vacuum, break the seal, and empty the filtrate into a waste beaker. Turn the vacuum back on, and leave the washed crystals in the funnel while the vacuum pump pulls air through them until they are dry, which usually takes about half an hour. You&#39;ll start working on your next recrystallization while you wait.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Recrystallization of <em>trans</em>-Cinnamic Acid<button class="expand">Expand</button>
	<p>In the second half of the lab, you&#39;ll recrystallize <em>trans</em>-cinnamic acid, which we&#39;ll just call cinnamic acid. Cinnamic acid is soluble in ethanol and nearly insoluble in water. So, you&#39;ll use a mixture of 95% ethanol and 5% water so that cinnamic acid is still soluble at high temperatures but less soluble at low temperatures.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-2">
		<div class="lab-step">To get started, fill a 5- or 10-mL graduated cylinder with deionized water and bring it to your hood.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Then, weigh 0.5 g of cinnamic acid, record its mass, and place it in a 25-mL Erlenmeyer flask.
		<h4><strong>Table 2: Recrystallization of<em> trans</em>-Cinnamic acid</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Compound</strong></td>
					<td><strong>Mass (g) </strong></td>
					<td><strong>Melting point (&#176;C) </strong></td>
				</tr>
				<tr>
					<td><em>trans</em>-Cinnamic acid</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Seed crystal (if used)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Recrystallized<em> trans</em>-cinnamic acid<br />
					<em>(subtract seed crystal if used)</em></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td></td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td><strong>Percent recovery</strong></td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/58/Table_2._Recrystallization_of_trans-Cinnamic_acid.xlsx" target="_blank">Click Here to download Table 2</a></div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Next, obtain 4 mL of 95% ethanol, and pour it into the flask containing cinnamic acid. Place the flask on a hotplate set to medium heat and stir the solution with a glass rod until the cinnamic acid dissolves, which usually takes 7 &#8211; 10 min.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Then, turn off the heat and use a Pasteur pipette to add 5 drops of deionized water to the solution. This reduces cinnamic acid solubility. <strong>Note:</strong> If you don&#39;t see precipitation, add up to 5 more drops of water one by one. Stop adding water if you see solids starting to form.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Then, remove the flask from the hotplate and let it cool to room temperature undisturbed.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">While you wait, get a small amount of the starting cinnamic acid and measure its melting point.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Once the flask has cooled to room temperature, inspect it for crystals. If you don&#39;t see any, gently scratch the inside of the flask under the solution with the glass rod and wait for 10 min. <strong>Note:</strong> If that still doesn&#39;t work, get a seed crystal of cinnamic acid from your instructor. Remember to weigh the seed crystal and record its mass before you add it to your solution.</div>
		</li>
		<li data-sub-note-item="2-9">
		<div class="lab-step">Once the flask is cool to the touch and contains several crystals, remake the ice baths with one ice bath shallow enough that the 25-mL flask will not be completely submerged.</div>
		</li>
		<li data-sub-note-item="2-10">
		<div class="lab-step">Refill the graduated cylinder with deionized water. Place the flask of cinnamic acid crystals in the shallow ice bath and the water-filled graduated cylinder in the other ice bath. Let the crystals grow for at least 15 min.</div>
		</li>
		<li data-sub-note-item="2-11">
		<div class="lab-step">Your acetanilide crystals should be dry by now, so measure their mass and melting point while you wait for your cinnamic acid to finish crystallizing. Turn off the vacuum and break the vacuum seal.</div>
		</li>
		<li data-sub-note-item="2-12">
		<div class="lab-step">Gently place the B&#252;chner funnel in a clean beaker and bring it to the balance. Measure and record the mass of your pure acetanilide crystals. Remember to subtract the mass of the seed crystal if you used one.</div>
		</li>
		<li data-sub-note-item="2-13">
		<div class="lab-step">Then, bring your crystals to the melting point apparatus and measure and record the melting point.</div>
		</li>
		<li data-sub-note-item="2-14">
		<div class="lab-step">Now, place a clean, dry B&#252;chner funnel with a new piece of filter paper in the filter flask and check on your cinnamic acid. Once it looks like most of the cinnamic acid has crystallized, wet the filter paper with cold deionized water.</div>
		</li>
		<li data-sub-note-item="2-15">
		<div class="lab-step">Start the vacuum and pour the contents of the cinnamic acid flask into the funnel. Scrape the remaining crystals out of the flask with the glass rod and rinse the flask with about 1 mL of cold water.</div>
		</li>
		<li data-sub-note-item="2-16">
		<div class="lab-step">Now, turn off the vacuum, break the seal, and pour the rest of the cold water into the funnel. Gently stir the crystals with the glass rod to wash them, being careful not to damage the filter paper.</div>
		</li>
		<li data-sub-note-item="2-17">
		<div class="lab-step">Turn on the vacuum to drain the funnel. Leave the vacuum running until the cinnamic crystals are dry.</div>
		</li>
		<li data-sub-note-item="2-18">
		<div class="lab-step">Place the B&#252;chner funnel in a beaker and bring it to the balance. Measure and record the mass of your pure cinnamic acid crystals. Remember to subtract the mass of the seed crystal if you used one. Then, measure the melting point of your recrystallized cinnamic acid.</div>
		</li>
		<li data-sub-note-item="2-19">
		<div class="lab-step">Now, dispose of your acetanilide and cinnamic acid in the designated solid waste container. Flush the filtrate down the drain with running water and pour leftover ice and water into the sink.</div>
		</li>
		<li data-sub-note-item="2-20">
		<div class="lab-step">Clean your glassware using your usual methods and put away your other lab equipment.</div>
		</li>
		<li data-sub-note-item="2-21">
		<div class="lab-step">Lastly, discard your used pipettes in the glass waste and throw out used filter paper and other trash in the lab trash container.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="3" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="3-1">
		<div class="lab-step">First, calculate the percent recovery for each compound. We expect that some of each compound stayed in solution, so these percentages will be below the reported purity of your starting material.</div>
		</li>
		<li data-sub-note-item="3-2">
		<div class="lab-step">Now, look at the differences in melting points between the starting material and the crystals. For each compound, the less pure starting material has a lower melting point and a broader range than the recrystallized compound.</div>
		</li>
		<li data-sub-note-item="3-3">
		<div class="lab-step">Lastly, compare your results to the literature values. The melting point of acetanilide is 114 &#176;C, and the melting point of <em>trans</em>-cinnamic acid is 133 &#176;C. The melting points of your crystals should span 1 &#8211; 2 &#176;C and should be at or just below those values.</div>
		</li>
	</ul>
	</li>
</ol>

Recrystallization of Acetanilide and trans-Cinnamic Acid - Procedure

Recristalización

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Recrystallization of AcetanilideExpand
	In this part of ...

Simple Distillation

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Simple Distillation<button class="expand">Expand</button>
	<p>In this lab, you will use simple distillation to separate a mixture of cyclohexane and toluene.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Before you start the lab, put on the appropriate personal protective equipment, including a lab coat, safety goggles, and gloves. This experiment must be conducted in a hood.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Assemble the distillation apparatus. Refer to the example set up that has been prepared by your instructor.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Then, set up the two stands next to each other in the hood. Place the magnetic stirrer on the base of one of the stands.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Set the heating mantle on top of the magnetic stirrer, and then plug it into the temperature controller.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Add 5 &#8211; 10 mL of sand to the heating mantle. This will allow more homogeneous heating of the round-bottom flask. Clamp the round-bottom flask to the stand above the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Now, obtain cyclohexane and toluene from your instructor. Measure 2 mL of cyclohexane using a volumetric pipette and dispense it into the round-bottom flask.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Then, use a clean volumetric pipette to measure 2 mL of toluene and add it to the flask.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Carefully insert a thermometer into an adapter by gently pushing and twisting it through the top.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Lightly grease the adapter with vacuum grease and insert it into the distilling head. Make sure that the thermometer bulb is below the bend of the distilling head. Then, lightly grease the joints of the distilling head.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Add a stir bar to the round-bottom flask and insert the distilling head into the round-bottom flask.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Now, clamp the condenser to the second stand with it oriented diagonally toward the side joint of the distilling head.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Connect one piece of tubing to the tap water faucet in the hood, and attach the other end to the inlet port of the condenser, which is located farthest from the distilling head.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Attach the second tubing to the outlet port, which is located closest to the distilling head, and place the other end of the tubing into the drain.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Connect the condenser to the distilling head. Then, lightly grease the joint of the condenser and attach the connecting tube. Place a 10-mL graduated cylinder below the outlet of the tube.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Gently lower the setup until the round-bottom flask is seated in the sand in the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Double-check all of the connections on your setup to make sure that they are tight and oriented correctly. Secure each joint with a plastic clip.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Now, slowly turn on the flow of water to the condenser. <strong>Note:</strong> Be careful not to turn on the water too quickly. If the water pressure is high, the tubing may pop off the condenser.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Turn the magnetic stirrer to the lowest setting, and set the temperature controller to heat the mantle to just above 90 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Once bubbles start forming in the liquid mixture, adjust the heat until the distillation rate is about 2 drops/min. You should also see drops forming on the thermometer bulb.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Record the temperature after every 2 drops that fall into the graduated cylinder or every minute.
		<h4><strong>Table 1: Distillation of toluene and cyclohexane</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Time (min) </strong></td>
					<td><strong>Distilled volume (mL) </strong></td>
					<td><strong>Temperature (&#176;C) </strong></td>
				</tr>
				<tr>
					<td style="text-align: center;">1</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">2</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">3</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">4</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">5</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">6</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">7</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">8</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">9</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">10</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">11</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">12</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">13</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">14</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">15</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/60/Table_1._Distillation_of_toluene_and_cyclohexane.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">When there is about 0.5 mL of the mixture remaining in the flask, which will look like a thin layer of liquid, turn off the heat and gently lift the glassware setup from the heating mantle. <strong>Note:</strong> Never heat the mixture until the flask is dry as this may cause an explosion.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Remove the stir plate with the heating mantle and set it aside.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Then, turn off the water to the condenser and allow the setup to cool completely. When it is cool, carefully disassemble the glassware.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Dispose of all solutions in the non-halogenated organic waste container. Clean your glassware with acetone followed by detergent and deionized water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Plot the dew point temperature versus the distilled volume during the experiment. We see that drops start to fall into the collection vessel at ~ 81 &#176;C, which is the boiling point of cyclohexane. As the distillation progresses, the temperature increases to almost 111 &#176;C, which is the boiling point of toluene.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Early in the distillation, the vapor is rich in cyclohexane. As the second milliliter is distilled, the temperature increases by ~ 20 &#176;C, which tells us that the amount of toluene in the vapor is increasing significantly. The temperature stabilizes as it approaches 111 &#176;C, which tells us that the vapor is rich in toluene towards the end of the distillation.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Look at a boiling point diagram for cyclohexane and toluene, with the mole percent of cyclohexane and toluene on the x-axis and the temperature on the y-axis. The solid line denotes the bubble point, and the dashed line denotes the dew point.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Use the dew point curve to determine the composition of the vapor throughout the distillation. For example, after 0.5 mL has been distilled, the condensing vapor is about 84 &#176;C. This corresponds to 95% cyclohexane on the dew point curve.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Once you know the composition of the vapor at each point, estimate the composition of the boiling mixture throughout the distillation. At room temperature, cyclohexane and toluene have nearly the same number of moles per milliliter, so think of the percentages in terms of volume.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">To determine how much of each liquid was distilled in each step, apply each percentage to the volume of liquid distilled since the previous measurement. This tells us that we distilled 1.9 mL of cyclohexane and 1.1 mL of toluene from our mixture of 2 mL of each liquid. Thus, our distillate was 63% cyclohexane and 37% toluene, and our remaining liquid mixture was 10% cyclohexane and 90% toluene.</div>
		</li>
	</ul>
	</li>
</ol>

Simple Distillation: Separation of a Mixture of Cyclohexane and Toluene - Procedure

Destilación simple

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Simple DistillationExpand
	In this lab, you will use ...