## Q. 9.47

$\Delta S = \frac{q_{rev}}{T}$

Lauren Huang 1H
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

### Q. 9.47

Question 9.47 in the sixth edition says:

Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible expansion; (b) isothermal, irreversible free expansion. Calculate deltaS(tot), deltaS(sys), and deltaS(surr) for each pathway.

Can someone explain the thought process for part b? More specifically, why is it that the change in entropy of the surroundings is zero when the change in entropy of the system is not zero?

Rian Montagh 2K
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: Q. 9.47

I think it has to do with the fact that no energy is transferred through a temp change or work of expansion to the surroundings. The only thing that changes is the volume of the system (free expansion = no work), and therefore the entropy increases with the volume increase.