Delta S equations

[Katherine Grillo 1B]

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]

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]

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]

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