## Vant Hoff Equation vs dG = -RTln(K)

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

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

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

Cole Woulbroun 1J
Posts: 56
Joined: Thu Jul 25, 2019 12:16 am

### Vant Hoff Equation vs dG = -RTln(K)

Before doing problem 5.55, I was under the impression that when you had a temperature that wasn't 298.15 K, you used the Vant Hoff Equation to determine the equilibrium constant since it accounts for the effect that a temperature change has on Kc. But in 5.55 the dG = -RTln(K) was used. What is the explanation for this? How do you know which of these equations to use when finding a K that is not at 298.15K?

Shivam Rana 1D
Posts: 106
Joined: Fri Aug 09, 2019 12:16 am

### Re: Vant Hoff Equation vs dG = -RTln(K)

You will have a different K at different temperatures since the equilibrium concentrations vary with temperature.