spontaneous reactions

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Jasleen Kahlon
Posts: 52
Joined: Wed Nov 21, 2018 12:19 am

spontaneous reactions

Postby Jasleen Kahlon » Sun Feb 23, 2020 10:44 pm

What exactly does a reaction being spontaneous mean in terms of thermodynamics, and what occurs when ∆S and ∆H are either both negative or both positive?

Ashley Wang 4G
Posts: 103
Joined: Wed Sep 11, 2019 12:16 am

Re: spontaneous reactions

Postby Ashley Wang 4G » Sun Feb 23, 2020 10:47 pm

A spontaneous reaction means it will tend to occur under the given conditions without an outside source of energy. Note that it says nothing about the speed of the reaction!

When ∆S and ∆H are either both negative or both positive, that is when the temperature dependence of the reaction becomes very important, as the magnitude of T will determine whether the reaction will be spontaneous.

Hope this helps!

Posts: 108
Joined: Sat Sep 28, 2019 12:15 am

Re: spontaneous reactions

Postby saigorijavolu2k » Sun Feb 23, 2020 10:50 pm

A negative delta S means that the reverse reaction is spontaneous. A positive delta S means that the forward reaction is spontaneous. A negative delta H means that it is exothermic and usually exothermic reactions are associated with being spontaneous because they release energy.

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