## Delta S Universe

$\Delta S = \frac{q_{rev}}{T}$

Petrina Kan 2I
Posts: 102
Joined: Fri Aug 30, 2019 12:17 am

### Delta S Universe

Can the equation $\bigtriangleup S_{univ}=\bigtriangleup S_{sys}+\bigtriangleup S_{surr}$ only apply to reversible reactions? Or can it apply to irreversible reactions as well?

Bryce Barbee
Posts: 103
Joined: Wed Sep 18, 2019 12:20 am

### Re: Delta S Universe

I think we only use it with reversible reactions but I am not 100% sure.

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

### Re: Delta S Universe

In a reversible reaction, delta S of the system is equal to delta S of the surroundings because delta S of the universe is 0. But I'm pretty sure that the general equation you described in your question applies to all reactions.

Frank He 4G
Posts: 50
Joined: Tue Nov 12, 2019 12:19 am

### Re: Delta S Universe

That equation can be applied to any situation. It's just telling us that the entropy of the surroundings and the system can be added to get the total change in entropy of the universe. If we're considering an irreversible reaction that happens spontaneously, it will have a positive delta S of the universe.