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Non Spontaneous Reaction vs Spontaneous Reverse Reaction

Posted: Sat Jan 27, 2018 10:37 pm
by Michelle Lee 2E
When entropy increases, the reaction is spontaneous. That means (delta)S is positive. When (delta)S is negative, would that mean the reverse reaction is spontaneous? If so, how should we think of the difference between a non spontaneous reaction and just a reverse reaction that is spontaneous?

When I say reverse reaction, I'm referring to products becoming reactants.

Re: Non Spontaneous Reaction vs Spontaneous Reverse Reaction

Posted: Sat Jan 27, 2018 10:45 pm
by Curtis Tam 1J
I think you don't really need to think in terms of forward or reverse reactions. Just know that in any reaction, it will tend to proceed in a certain way. If the forward reaction doesn't proceed spontaneously, then I believe it should be spontaneous in the reverse direction.

Re: Non Spontaneous Reaction vs Spontaneous Reverse Reaction

Posted: Sun Jan 28, 2018 1:58 pm
by Srbui Azarapetian 2C
In the forward reaction if entropy was positive and enthalpy negative, the reaction is spontaneous at all temperatures. In the case of the same reaction, except the reverse, the reaction would have negative entropy and enthalpy positive, which is the most unfavorable set of conditions, meaning the reaction is not spontaneous.