Spontaneity and Entropy


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Rachel Yu 1G
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Joined: Fri Aug 09, 2019 12:15 am

Spontaneity and Entropy

Postby Rachel Yu 1G » Mon Feb 10, 2020 10:17 am

What is the relationship between entropy and spontaneous reactions? Does it always depend on the Gibbs free energy equation?

Justin Sarquiz 2F
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

Re: Spontaneity and Entropy

Postby Justin Sarquiz 2F » Mon Feb 10, 2020 10:34 am

Spontaneity is determine using the Gibbs Free energy equation G=H-TS. Since -G is spontaneous, we want a large and positive delta S. However, you would need to plug in the values for temperature and enthalpy to really determine spontaneity because enthalpy could be greater than TS.

805422680
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Joined: Sat Sep 14, 2019 12:16 am

Re: Spontaneity and Entropy

Postby 805422680 » Mon Feb 10, 2020 11:03 am

An increase in entropy leads to a decrease in Gibbs free energy. Both these situations represent a spontaneous reaction

Vicki Liu 2L
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

Re: Spontaneity and Entropy

Postby Vicki Liu 2L » Mon Feb 10, 2020 11:18 am

This question can also be considered more conceptually using the second law of thermodynamics. Since the entropy of the universe is always increasing, you can think of processes that increase entropy as naturally occurring, or spontaneous. However, whether or not delta G is actually negative depends on the magnitude of delta S relative to delta H.


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