## H and S temperature dependence [ENDORSED]

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

Gabriella Bates 2L
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Joined: Thu Jul 11, 2019 12:15 am

### H and S temperature dependence

When deriving the Van't Hoff equation in the book, they write, "It is usually reasonable to assume that delta H and delta S are both approximately independent of temperature over the range of temperatures of interest." However, in our other equations they both are dependent of temperature (for example, S = q/T). Why does the book make this assumption?

Chem_Mod
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### Re: H and S temperature dependence  [ENDORSED]

As I discussed in class what is being said here is the difference in enthalpy between reactants and products, and the difference in entropy between reactants and products, are for some reactions not temperature dependent.

As emphasized in class the entropy of the reactants and products are definitely temperature dependent, but their difference in entropy can be the same at different temperatures.

I discussed the example of heating a test-tube and entropy of the reactants and products both increase by the same amount, resulting in their entropy difference not changing.

Hope this helps.