## 4.11

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

Karina Koo 2H
Posts: 49
Joined: Fri Sep 28, 2018 12:24 am

### 4.11

During the test of an internal combustion engine, 3.00L of nitrogen gas at 18.5 degrees C was compressed suddenly (and irreversibly) to .500L by driving in a piston. In the process the temperature of the gas increased to 28.1 degrees C. Assume ideal behavior and 1.00 mole of nitrogen gas. What is the change in entropy of the gas?

In the student manual, they used the equation change in s= nRTln(T2/T1) instead of change in S= nCln(T2/T1) why is this?

Eshwar Venkat 1F
Posts: 32
Joined: Fri Sep 28, 2018 12:22 am

### Re: 4.11

You are actually supposed to use both equations, the reason being that both irreversible expansion and heating of the system occur. The change in entropy of the gas is the sum of the answers you get from plugging into both equations.