conceptual question about change in entropy due to both temp and vol  [ENDORSED]

Volume:
Temperature:

Moderators: Chem_Mod, Chem_Admin

Annie Lieu-1H
Posts: 68
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 1 time

conceptual question about change in entropy due to both temp and vol

Postby Annie Lieu-1H » Sun Feb 04, 2018 5:24 pm

I understand that it's a 2 step process that we end up adding all together. But why do we use constant volume for the temperature equation? The volume is changing, so how is it heat capacity at constant volume?

Janet Nguyen 2H
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

Re: conceptual question about change in entropy due to both temp and vol

Postby Janet Nguyen 2H » Sun Feb 04, 2018 6:42 pm

We are assuming, by using the two step process, that first the volume increases and then the temperature increases(or decreases whatever the problem says) so when the temperature is changing, the volume has already changed and is now constant

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

Re: conceptual question about change in entropy due to both temp and vol  [ENDORSED]

Postby Chem_Mod » Sun Feb 04, 2018 6:47 pm

The change occurs in one step with both volume and temperature changing at the same time.
But since entropy is a state function we can separate it into two steps to make the calculation possible for each step, and then add them.

The overall process is separated into two steps to make the individual calculations easier:

1: Decreased the volume, keep temperature constant.

2: Increase the temperature, keep volume constant.

I will likely discuss this in class during my review as many students have asked this.

Make sure to discuss it in the Workshops, Step-Up Sessions, Discussion Sections, Office Hours, and Reveiw Sessions.

Jessica Lutz 2E
Posts: 56
Joined: Fri Sep 29, 2017 7:04 am

Re: conceptual question about change in entropy due to both temp and vol

Postby Jessica Lutz 2E » Sun Feb 04, 2018 6:51 pm

Is there a reason you do it in that order? Or would you get the same answer if you changed the temperature first with a constant volume?


Return to “Entropy Changes Due to Changes in Volume and Temperature”

Who is online

Users browsing this forum: No registered users and 0 guests