1 lgasl

Fig. 6.2 Modified Joule apparatus

If an equation of state appropriate to a nonideal gas is used in the bracketed term in Eq (6.30), the temperature change on expansion can be predicted. If the initial pressure is sufficiently high and the initial temperature low enough, the nonideal effect will be large enough to be measured.

Example: What is the change in temperature of nitrogen when the specific volume initially at 20oC and 10 MPa is doubled at constant internal energy?

Noting that CV = CV0 = 7/2R = 29.1 J/mole-K, and using Eq (2.3) for the equation of state in Eq (6.30) yields:

Integrating from v1 to 2v1 gives a temperature change of:



It is clear from this equation that measurement of the gas temperature decrease in a Joule expansion provides a means of experimentally determining the coefficient a in the Van der Waals equation under conditions in which the gas exhibits nonideal behavior.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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