## 5J.15

$\ln K = -\frac{\Delta H^{\circ}}{RT} + \frac{\Delta S^{\circ}}{R}$

zfinn
Posts: 106
Joined: Fri Aug 30, 2019 12:16 am

### 5J.15

can someone explain problem 5J.15? even after looking at the solutions guide i'm still a bit confused on how to start, and also just the steps to solve the equation. thanks so much!

Alicia Lin 2F
Posts: 83
Joined: Wed Sep 18, 2019 12:17 am

### Re: 5J.15

Because G=-RTlnK, you can rearrange this equation to solve for K so K=e^(-G/RT). For the 25 degree part, find G of the reaction by taking the standard Gibbs energy of products minus that of reactants. After finding G of reaction, plug that into the equation solving for K where R is ideal gas constant (make sure G and R have the same units) and T is 298K. Solve for K.
For the 150 degree part, you have to find the enthalpy and entropy of the reaction separately using standard values. And then use G=H-TS to solve for G at this temperature (you have to do this because it is nonstandard temperature). Then you plug in G to the K equation as you did for the first part.