## Entropy in Van't Hoff Equation

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

BNgo_2L
Posts: 95
Joined: Wed Sep 11, 2019 12:17 am

### Entropy in Van't Hoff Equation

For the Van't Hoff equation, is entropy always constant? If not, in what instances would it not be constant?

Jordan Young 2J
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### Re: Entropy in Van't Hoff Equation

I believe we assume that entropy remains constant because I think we would normally use that equation to find equilibrium constants based on temperature. Also, entropy gets cancelled when you try to find K at two different temperatures if delta H is know

Chris Tai 1B
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Joined: Sat Aug 24, 2019 12:16 am

### Re: Entropy in Van't Hoff Equation

The reason we assume the entropy is constant is not that we think that the entropy is the same value, but that the difference in that entropy between reactants and products is the same at two different temperatures. The entropy may indeed be higher or lower at given temperatures, but the difference still remains the same, which is why we can cancel them out when we prove Van't Hoff's equation by subtracting lnK2 - lnK1.

Fatemah Yacoub 1F
Posts: 114
Joined: Thu Jul 11, 2019 12:16 am

### Re: Entropy in Van't Hoff Equation

The change in entropy is constant because the difference in entropy between the reactants and products at 2 different temperatures is the same. The entropy is different at two different temperatures, but for Van't Hoff we are using the net change go entry which is constant.

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