Delta S and what it favors?

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

Johnson Thai 1L
Posts: 19
Joined: Wed Sep 21, 2016 2:59 pm

Delta S and what it favors?

Why does positive Delta S favor forward processes and why does negative Delta S not? Does "forward" refer to a reaction where a substance goes from a lower energy state to a higher one? Clarification please, thanks.

Christian Hardoy 3F
Posts: 41
Joined: Fri Jul 15, 2016 3:00 am

Re: Delta S and what it favors?

I'm not sure what you mean by "forward processes," but positive delta S means an increase in disorder. If a certain reaction under a certain set of conditions has a positive value of delta S then it means that the reaction represents an increase in disorder and will occur spontaneously. The reverse reaction will have a negative value of delta S and will not be spontaneous.

Michelle Kam 1F
Posts: 10
Joined: Wed Sep 21, 2016 2:58 pm

Re: Delta S and what it favors?

A positive Delta S indicates a favorable or spontaneous process. This means that the reaction will proceed without any energy input.
A negative Delta S indicates an unfavorable or nonspontaneous process, meaning that the reaction will require some energy to proceed.
I don't think it'd be too helpful to think of this as forward or backward.