## 11.83

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

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

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

Caitlin Mispagel 1D
Posts: 47
Joined: Tue Oct 10, 2017 7:13 am

### 11.83

For question 11.83: Calculate the equilibrium constant at 25 C and at
150 C for each of the following reactions, using data available in Appendix 2A:
(a) NH4Cl(s) <--> NH3(g) + HCl(g)
(b) H2(g) + D2O(l) <--> D2(g) + H2O(l)
Is the calculation different when the temperature is at 150 other than the value of T changing? I am using the equation delta G=-RTlnK and I am getting the right answers when calculating K at 25 degrees but when I do the same calculation using 150 degrees I am getting wrong answers.

Matthew Lin 2C
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

### Re: 11.83

You should be able to use the same equation and values and just change T to get the right answer. Just make sure you use Kelvin!

melissa carey 1f
Posts: 53
Joined: Fri Sep 29, 2017 7:06 am

### Re: 11.83

This isn't what the solution manual says? Can someone explain how to approach this problem?

Diego Zavala 2I
Posts: 65
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: 11.83

For 298K, you can use the equation $\Delta G^{\circ} =-RTlnK$ to find the K value. For 423K, use the equation $ln(K_{2}/K_{1})=\Delta H/R [(1/T_{1})-(1/T_{2})]$