## Homework 9.51

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

Kelsey Jug 1J
Posts: 38
Joined: Wed Sep 21, 2016 2:59 pm

### Homework 9.51

9.51 asks, why are so many exothermic reactions spontaneous?

the answer gives the equation deltaG = deltaH - TdeltaS and says that exothermic reactions tend to be spontaneous because the result in an increase in the entropy of the surroundings.

My question is, does the deltaS in the equation represent change in entropy of the surroundings or of the system?

vsyacoubian2A
Posts: 63
Joined: Fri Jul 22, 2016 3:00 am

### Re: Homework 9.51

The Delta S should be for whatever you are calculating delta G in. So if delta G is for the system, delta S would need to be for the system. The same applies for the surroundings. Entropy tends to be a chain reaction. If one reaction is spontaneous, the creation of entropy in the surroundings can create enough free energy to kickstart another reaction. (coupling reactions)

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