Different entropy measures 4.37

[Jeffrey Hablewitz 2I]

What is the difference between ΔS and ΔS_total? And why is ΔS_total always greater than 0 in a spontaneous process if ΔS is necessarily positive in a spontaneous reaction?

[Lillian Ma 1I]

I think ΔStotal refers to the ΔS of both the system and the surroundings added up. The requirement for a process to be spontaneous is for ΔStotal to be positive, however ΔS does not have to be positive in order for the process to be spontaneous because the other ΔS of either the system or the surrounding can bring ΔStotal back up to being positive. I hope this helped!

[Jeffrey Hablewitz 2I]

Thanks! That was very helpful.

[Daniel Huynh 2J]

Plus, in an equation ΔS usually refers to the system (the sys at the end is dropped).

[Susanna Givan 2B]

Delta S total is about the total entropy of the surroundings and the system and Delta S is just about the system you are referring to.