## Gibbs free energy and spontaneity

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

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

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

Liam Maxwell 2E
Posts: 53
Joined: Fri Sep 29, 2017 7:07 am

### Gibbs free energy and spontaneity

Is calculating G the only way to officially conclude spontaneity? Because based on the equation calculating merely entropy or enthalpy doesn't appear to be enough.

Aijun Zhang 1D
Posts: 53
Joined: Tue Oct 10, 2017 7:13 am

### Re: Gibbs free energy and spontaneity

Yeah, basically you need delta G to determine spontaneity.
Or you can use K to indirectly find the spontaneity at equilibrium.

Kyle Sheu 1C
Posts: 87
Joined: Fri Jun 23, 2017 11:39 am

### Re: Gibbs free energy and spontaneity

A spontaneous process is one that increases the entropy of the universe, which we can calculate by taking the sum deltaSsys + deltaSsurr.

So deltaG is not the ONLY way to determine thermodynamic favorability, but as it is often difficult to measure the change in entropies of system and surroundings, we make use of the changes in enthalpy and entropy of the system to calculate deltaG as an applicable method of determining spontaneity.

Caroline LaPlaca
Posts: 30
Joined: Sat Jul 22, 2017 3:01 am

### Re: Gibbs free energy and spontaneity

Yes because entropy and enthalpy both affect the chance of spontaneity.