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Chapter 20

The First Law of Thermodynamics

Sistemi termodinamici
Sistemi termodinamici
A thermodynamic system is a set of objects whose thermodynamic properties are of interest. The system is considered to be embedded in its surroundings or ...
Lavoro svolto durante la modifica del volume
Lavoro svolto durante la modifica del volume
In mechanics, work is done on an object when the force acting on it displaces the object. In thermodynamics, work done on a system can be estimated when ...
Percorso tra gli stati della termodinamica
Percorso tra gli stati della termodinamica
Consider the two thermodynamic processes involving an ideal gas that are represented by paths AC and ABC in Figure 1: In the first process for path A to ...
Calore ed espansione libera
Calore ed espansione libera
The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states—that is, on the path. ...
Energia interna
Energia interna
The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic ...
Primo principio della termodinamica
Primo principio della termodinamica
A change in the internal energy of a system depends on the the net heat transfer into the system and the net work done by the system. The first law of ...
Primo principio della termodinamica: risoluzione dei problemi
Primo principio della termodinamica: risoluzione dei problemi
The first law of thermodynamics states that the change in internal energy of the system is equal to the net heat transfer into the system minus the net ...
Processi ciclici e sistemi isolati
Processi ciclici e sistemi isolati
A thermodynamic system with zero heat exchange and work is an isolated system. For these systems, the internal energy remains constant. In the case of a ...
Processi isotermici
Processi isotermici
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to ...
Processi isocorici e isobarici
Processi isocorici e isobarici
A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or ...
Capacità termiche di un gas ideale I
Capacità termiche di un gas ideale I
Heat capacity is the ratio of heat absorbed by the substance corresponding to its temperature change. It is also called thermal capacity and the SI unit ...
Capacità termiche di un gas ideale II
Capacità termiche di un gas ideale II
For a system that undergoes a thermodynamic process at a constant volume condition, the heat absorbed is used only to increase the system's internal ...
Capacità termiche di un gas ideale III
Capacità termiche di un gas ideale III
The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents ...
Processi adiabatici per un gas ideale
Processi adiabatici per un gas ideale
When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, ...
Pressione e volume in un processo adiabatico
Pressione e volume in un processo adiabatico
Free expansion of a gas is an adiabatic process. However, there are few differences between free expansion and adiabatic expansion. During free expansion, ...
Lavoro svolto in un processo adiabatico
Lavoro svolto in un processo adiabatico
Consider the adiabatic compression of an ideal gas in the cylinder of an automobile diesel engine. The gasoline vapor is injected into the cylinder of an ...
Potenziali termodinamici
Potenziali termodinamici
Thermodynamic potentials are state functions that are extremely useful in analyzing a thermodynamic system. They have dimensions of energy. The four ...
Relazioni termodinamiche di Maxwell
Relazioni termodinamiche di Maxwell
Maxwell's thermodynamic relations are very useful in solving problems in thermodynamics. Each of Maxwell's relations relates a partial ...
Effetto Joule-Thomson
Effetto Joule-Thomson
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous ...
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