## 11.21

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

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

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

lizzygaines1D
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

### 11.21

Calculate the standard Gibbs Free energy for I2(g)--->2I(g) when K=6.8 at 1200 K. So using deltaG=deltaGrxn+RTlnQ, I understand how to solve for everything else, but how would you find Q if you are not given a pressure or anything for the products and reactants?

Samantha Kan 2L
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

### Re: 11.21

For this question, you don't need Q because the problem is assuming the reactants and products are at equilibrium. To find the standard Gibbs free energy, you just have to use the equation delta G = -RTlnK. Hope this helps!

Justin Chu 1G
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 1 time

### Re: 11.21

Yea when the reaction is at equilibrium, you can simply use the K that's given to you.