UA Karen Week 4 #6  [ENDORSED]


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Aya Shokair- Dis 2H
Posts: 58
Joined: Fri Sep 29, 2017 7:07 am

UA Karen Week 4 #6

Postby Aya Shokair- Dis 2H » Tue Feb 13, 2018 7:38 pm

A sample of 1 mol of gas initially at 1 atm and 298K is heated at constant pressure to
350K, then the gas is compressed isothermally to its initial volume and finally it is cooled
to 298K at constant volume. Which of the following values is 0?
a. ΔSsurr and ΔG
b. ΔSsys and ΔSsurr
c. q and w
d. W
e. ΔG and ΔSsys

Can someone please walk me through this?
Thanks bc I'm so confused

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Re: UA Karen Week 4 #6  [ENDORSED]

Postby Chem_Mod » Tue Feb 13, 2018 11:13 pm


To approach this question, I would first try to draw out a PV diagram of the situation. Put pressure as the x axis and volume as the y axis, place points where each state is at, and connect the points. If you did that correctly, you should see that the system and loop is closed, and you return to the initial state after everything that occurs. Since final state = initial state, all properties that are state functions would be 0. Answer choices C and and D contain properties that are not state functions, which automatically eliminates those answers. ΔS surrounding cannot be 0, because the 2nd law states that ΔS total must be greater than 0. That eliminates choice A and B, leaving answer choice E as the correct answer.

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