## Van't Hoff equation on 5J.15

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

asannajust_1J
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Joined: Wed Sep 11, 2019 12:16 am
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### Van't Hoff equation on 5J.15

The question asks you to calculate the K value at 25C and 150C. I correctly found the K value for the reaction at 25 C using equation G=-RTlnK, but am not sure how to apply the vant hoff equation at 150C.. the reaction is NH4CL -> NH3 + HCl

Sjeffrey_1C
Posts: 108
Joined: Wed Feb 20, 2019 12:17 am

### Re: Van't Hoff equation on 5J.15

At 150 C, I used the equation ln (k2/k1) = delta H naught/R * ((1/T1)-(1/T2))

You plug in the values you already know... For example for part a K1 = 1.07 x 10^-16. T1 = 298. K and T2 = 423. K

You solve for delta H naught using the values in the appendix. R is a constant.

This leaves you with an equation that allows you to solve for K2.