## Calculating Gibbs Free Energy

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

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

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

siannehazel1B
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

### Calculating Gibbs Free Energy

How do we know when to do the difference of sums vs when to use the equation $\Delta G= \Delta H-T\Delta S$ to solve for gibbs free energy?

Lauren Seidl 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

### Re: Calculating Gibbs Free Energy

You use difference of sums to find Gibbs free energy when you are using the Gibbs free energy of formation for the reactants and products. If you are given entropy, enthalpy, and temperature, then you would use deltaG=deltaH - TdeltaS.

RohanGupta1G
Posts: 34
Joined: Sat Jul 22, 2017 3:00 am

### Re: Calculating Gibbs Free Energy

Usually i look at what information is given and then am able to determine which equation works.

Pooja Nair 1C
Posts: 55
Joined: Thu Jul 13, 2017 3:00 am

### Re: Calculating Gibbs Free Energy

Use difference of sums when the information given pertains to the Gibbs free energy of products or reactants, and the other equation when given entropy and enthalpy. Determine what information the question gives you and then you can choose an equation to plug into accordingly

Justin Bui 2L
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

### Re: Calculating Gibbs Free Energy

It all depends on what is available to you and then with that, you'd be able to decide what to use. But there's usually a chemical equation or steps when it's a difference of sums situation.