## Spontaneity and Entropy

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

Rachel Yu 1G
Posts: 113
Joined: Fri Aug 09, 2019 12:15 am

### Spontaneity and Entropy

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

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
Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

### Re: Spontaneity and Entropy

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

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.