(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

One mole of a monatomic gas first expands isothermally, then contracts adiabatically. The final pressure and volume of the gas are twice its initial pressure and volume. (P_{f}=2P_{i}and V_{f}=2V_{i})

Find the net change in the entropy of the gas.

2. Relevant equations

3. The attempt at a solution

I found the entropy change for the first step. Let the volume between the two steps be V_{m}.

TV^{γ-1}= constant, so V_{m}= 2^{2.5}V_{i}

ΔS = nR ln(V_{m}/V_{i}) = 1.73 nR

But I have no idea about the entropy change of the second step. What is the entropy change for an adiabatic process? Isn't dQ=0 ?

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# Homework Help: An entropy change question?

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