Delta S equations

Volume:
Temperature:

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Katherine Grillo 1B
Posts: 69
Joined: Fri Sep 28, 2018 12:28 am

Delta S equations

Postby Katherine Grillo 1B » Wed Feb 13, 2019 12:20 pm

I'm confused about the different delta S equations. When does delta S equal q/t vs nRln(V2/V1) vs nCln(T2/T1)?

MaanasO 1A
Posts: 72
Joined: Fri Sep 28, 2018 12:26 am

Re: Delta S equations

Postby MaanasO 1A » Wed Feb 13, 2019 12:29 pm

Hi Katherine!

dS = q/t when you're dealing with a reversible process. dS = nRln(Vf/Vi) when the process is isothermal. dS = nCln(Tf/Ti) when there's a change in temperature associated with the change in entropy. Your C value will change based on whether your volume (Cv) or pressure (Cp) are constant.

Hope that helps!

705192887
Posts: 77
Joined: Fri Sep 28, 2018 12:18 am

Re: Delta S equations

Postby 705192887 » Wed Feb 13, 2019 12:51 pm

MaanasO 1A wrote:Hi Katherine!

dS = q/t when you're dealing with a reversible process. dS = nRln(Vf/Vi) when the process is isothermal. dS = nCln(Tf/Ti) when there's a change in temperature associated with the change in entropy. Your C value will change based on whether your volume (Cv) or pressure (Cp) are constant.

Hope that helps!


In the last sentence you said the C value will change depending on whether volume or pressure are constant. Could you elaborate on that?

Zenita Leang 2K
Posts: 67
Joined: Fri Sep 28, 2018 12:28 am

Re: Delta S equations

Postby Zenita Leang 2K » Wed Feb 13, 2019 1:06 pm

If you have a constant volume then you will use Cv which is equivalent to R. If it has a constant pressure, then you will use Cp which is equivalent to R. R is the constant on the constants and equations sheet.


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