## Which value of R to use?

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

Clara Rehmann 1K
Posts: 53
Joined: Fri Sep 29, 2017 7:03 am

### Which value of R to use?

Hi,
I'm a bit confused as to deciding which value of R to use when calculating entropy - Lavelle's cheat sheet has a couple different values (based on changes in units). I try to base my choice of R off of the other units I am provided with when solving a problem, but that doesn't seem to always work. Does anyone have any tips?

Angel Ni 2K
Posts: 50
Joined: Sat Jul 22, 2017 3:01 am

### Re: Which value of R to use?

The method you mentioned should work as long as you make sure that you end up with the units that correspond to the variable you are solving for.

Emma Ward 2C
Posts: 32
Joined: Fri Sep 29, 2017 7:05 am

### Re: Which value of R to use?

The values of R are based of the units. It helps to write out all of the units while working on a problem so you keep track of everything.

104922499 1F
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

### Re: Which value of R to use?

The method you have been using should work because the units and conversions should be equal.