### 11.83

Posted:

**Sun Feb 11, 2018 8:27 pm**Why do we need to find delta S?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=135&t=27432

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Posted: **Sun Feb 11, 2018 8:27 pm**

Why do we need to find delta S?

Posted: **Sun Feb 11, 2018 8:38 pm**

We are looking for K, which can be found with the equation ΔG = -RTlnK. So first we need to find ΔG. We can do that by using the equation ΔG = ΔH - TΔS. We are given the temperature, but we still need to find ΔH and ΔS in order to find ΔG.

Posted: **Mon Feb 12, 2018 1:45 am**

For 11.83, we need to find both delta H and delta S in order to use the formula delta G = delta H - T delta S to find delta G. We are not given the delta G, so we would need to find this. Once you find delta G, you can just use the formula delta G = -RTlnK to find K, the equilibrium constant.

Posted: **Mon Feb 12, 2018 5:51 pm**

Why do we need to find ∆G by using ∆H-T∆S instead of by using ∑∆G(products)-∑∆G(reactants)? I tried this with the ∆G values in the appendix but I got a different answer

Posted: **Mon Feb 12, 2018 11:43 pm**

^^ Yes! So did I, would it be wrong to use ∑∆G(products)-∑∆G(reactants)?