## 6th edition 9.57

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

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

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

Karyn Nguyen 1K
Posts: 72
Joined: Fri Apr 06, 2018 11:04 am

### 6th edition 9.57

For question 9.57 in the 6th edition, I don't get how to calculate $\Delta H^{\circ}_{r}$. In the solution manual, it says $\Delta H^{\circ}_{r}$ = 2 $\Delta H^{\circ}_{f}$(H2O, aq) - 2 $\Delta H^{\circ}_{f}$(H2O2,l). Where did H2O,aq come from? Also, what is the general formula for $\Delta H^{\circ}_{r}$?

Karyn Nguyen 1K
Posts: 72
Joined: Fri Apr 06, 2018 11:04 am

### Re: 6th edition 9.57

Karyn Nguyen 1K wrote:For question 9.57 in the 6th edition, I don't get how to calculate $\Delta H^{\circ}_{r}$. In the solution manual, it says $\Delta H^{\circ}_{r}$ = 2 $\Delta H^{\circ}_{f}$(H2O, aq) - 2 $\Delta H^{\circ}_{f}$(H2O2,l). Where did H2O,aq come from? Also, what is the general formula for $\Delta H^{\circ}_{r}$?

I figured out you can solve $\Delta H^{\circ}_{r}$ by using the equation we have been taught like normal (sum of products minus sum of reactants) and still get the same as the answer as the one in the solutions manual!