## enthalpy, entropy, Gibbs Free Energy signs

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

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

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

Deepika Pugalenthi 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### enthalpy, entropy, Gibbs Free Energy signs

For what signs of enthalpy, entropy, and Gibbs Free Energy is a reaction spontaneous and when is it not spontaneous?

Helen Zhao 1F
Posts: 31
Joined: Fri Sep 28, 2018 12:20 am

### Re: enthalpy, entropy, Gibbs Free Energy signs

In a spontaneous reaction, enthalpy is negative, entropy is positive and Gibbs Free Energy is negative. In a nonspontaneous reaction, enthalpy is positive, entropy is negative and Gibbs Free Energy is positive.

Patrick Cai 1L
Posts: 93
Joined: Fri Sep 28, 2018 12:25 am

### Re: enthalpy, entropy, Gibbs Free Energy signs

There are two other cases where temperature has to be considered. If enthalpy is positive but entropy is also positive, at high temperatures the reaction would have a negative change in free energy and is spontaneous; if enthalpy is negative but entropy is also negative, at low temperatures the reaction would have a negative change in free energy and is also spontaneous.

LedaKnowles2E
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

### Re: enthalpy, entropy, Gibbs Free Energy signs

When Gibbs free energy is negative the process is spontaneous.