JoVE Logo
Faculty Resource Center

Sign In

Abstract

Protocol

Representative Results

Materials

Chemistry

Melting Points

Published: Not Published

  1. Preparation of the Laboratory

    Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

    • To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves.
    • Prepare a mixture of urea and benzoic acid in a mass ratio of 4 to 1. Tare a weighing boat and measure 0.48 g of urea. Use a powder funnel to transfer the urea to a glass vial.
    • Weigh 0.12 g of benzoic acid and add it to the vial. Mix the solids thoroughly by stirring with a spatula and shaking the closed vial. Label the vial as ‘urea with unknown’.
    • Obtain enough naphthalene for each group to have 1 mg.
    • Label a 50-mL beaker for solid waste and set it along with the naphthalene, the bottle of pure urea, and the mixture of urea and benzoic acid near the balance.
    • For each group, pour about 150 mL of mineral oil into a 250-mL beaker. Distribute the baths to the student’s workstations before the lab.
    • Place a 2-ft section of glass tubing on a communal bench for students to use during the lab.
    • Set out the following glassware and equipment at each student lab station (we suggest that students work in pairs):
       1    Stir bar
       1    Stirring hotplate
       1    Lab stand
       1    Thermometer clamp
       1    Digital thermometer (pre-calibrated, 60 – 150°C)
       4    Melting point capillary tubes
       3    Metal spatulas
       3    Watch glasses
       1    Rubber band

Log in or to access full content. Learn more about your institution’s access to JoVE content here

What is the melting point?

The melting point of a compound is measured as a range of temperatures from where the solid phase transitions into the liquid phase. The upper limit of the range is the temperature where the first liquid drops are observed, and the lower limit of the range is the temperature where the solid phase has fully turned into liquid.

Why is the melting point important?

The melting point is.......

Log in or to access full content. Learn more about your institution’s access to JoVE content here

  • Lab stand
    5
  • Thermometer clamp
    5
  • Digital thermometer (60-150°C range)
    5
  • Melting point capillary tube
    20
  • Rubber bands
    5
  • Watch glass
    15
  • 250-mL glass beaker
    5
  • Metal spatula
    15
  • Benzoic acid
    0.5 g
  • Napthalene
    5 mg
  • Urea
    1 g
  • Stir bars
    5
  • Stirring hotplate
    5
  • 2-mL glass vial with cap
    1
  • 50-mL glass beaker
    1
  • Powder funnel
    1
  • Glass tube (2')
    1
  • Mineral oil
    750 mL
  • Weighing boats
    -1 Dependent on lab size
  • Top-loading or analytical balance (at least 1)
    -1 Dependent on lab size
  • Magnetic wand
    -1 Dependent on lab size

This article has been published

Video Coming Soon

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2024 MyJoVE Corporation. All rights reserved