## Quiz #1 Preparation #12

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

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

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

JaeHoCho1B
Posts: 16
Joined: Sat Jul 09, 2016 3:00 am

### Quiz #1 Preparation #12

Hello! I was wandering for quiz preparation quiz 12 on page 116 that are we supposed to use the following equation?
delta G= delta H - T(Delta S). If yes, do we add all up the given delta H and subtract with the given Temperature times the sum of delta S.

**Sorry I can't post chart, but the question is: "Calculate the standard Gibbs free energy for the following reaction at 298 K. Fe2O3 + C(s, graphite)----->Fe(s) + CO2(g)

Michelle_Nguyen_3F
Posts: 40
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Quiz #1 Preparation #12

Yes, you would need to use $\Delta G = \Delta H -T\Delta S.$ Since you know that $\Delta H_{rxn}= \Sigma \Delta H_{f}(products)-\Sigma \Delta H_{f}(reactants)$ and $\Delta S_{rxn}= \Sigma \Delta S(products)-\Sigma \Delta S(reactants)$, then we can use $\Delta G = \Delta H -T\Delta S$ to find the standard Gibbs free energy. Don't forget to balance the equation!