## Midterm 2016 Q2

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

Chiao-Wei Cheng 3e
Posts: 16
Joined: Wed Sep 21, 2016 2:55 pm

### Midterm 2016 Q2

My question is why is the change in state of dry ice not included in the calculations for q?

stephanieyang_3F
Posts: 62
Joined: Wed Sep 21, 2016 2:55 pm

### Re: Midterm 2016 Q2

If you look closely at the question... it says "acetonitrile BEFORE the acetonitrile begins to freeze", so you wouldn't need to include the heat required to change the acetonitrile from liquid to solid. Hope I helped!

Chiao-Wei Cheng 3e
Posts: 16
Joined: Wed Sep 21, 2016 2:55 pm

### Re: Midterm 2016 Q2

What about dry ice? Do we assume that it doesn't sublime?

stephanieyang_3F
Posts: 62
Joined: Wed Sep 21, 2016 2:55 pm

### Re: Midterm 2016 Q2

Yes. The question doesn't give you any information about when dry ice sublimates so you'd assume it wouldn't change states during the process.

Chiao-Wei Cheng 3e
Posts: 16
Joined: Wed Sep 21, 2016 2:55 pm

Thanks!