9.13 Changes in Entropy

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

Sue_Park_2D
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Joined: Wed Sep 21, 2016 2:57 pm

9.13 Changes in Entropy

I had a question on 9.13.
"During the test of an internal combustion engine, 3.00 L of nitrogen gas at 18.5 C was compressed suddenly (and irreversibly) to 0.500 L by driving in a piston. In the process, the temperature of the gas increased to 28.1 C. Assume ideal behavior. What is the change in entropy of the gas?"

I understand that there are two entropies to calculate to get the total entropy:
- the decrease of entropy caused by the decrease in volume using the equation nR ln(V2/V1)
- the increase of entropy caused by the increase in temperature.....

I thought that we had to use the equation nC ln(T2/T1) but solutions manual uses nR ln (T2/T1) I'm confused as to why we use this equation instead.

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Re: 9.13 Changes in Entropy

You should use C, it is a typo in the solutions manual.
https://lavelle.chem.ucla.edu/wp-conten ... rs_6Ed.pdf