## oxygen has 0 Gibbs free energy of formation

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

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

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

Hannah Chew 2A
Posts: 76
Joined: Fri Sep 29, 2017 7:05 am
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### oxygen has 0 Gibbs free energy of formation

Why does oxygen (and other naturally occurring elements like I2, H2, K) all have 0 Gibbs free energy, even though there is some numerical value for molar entropy still listed in the Appendix? Doesn't delta G formation = delta H formation - T (delta molar entropy)?

Emily Duggan 1F
Posts: 42
Joined: Fri Sep 29, 2017 7:07 am

### Re: oxygen has 0 Gibbs free energy of formation

Yes, and the enthalpy of formation of elements in their standard state, like H2, O2 and I2, are all 0. So when you calculate delta G formation, the numerator is 0 so the delta G is 0. Hope this helps!

Chris Lamb 1G
Posts: 58
Joined: Fri Jun 23, 2017 11:39 am

### Re: oxygen has 0 Gibbs free energy of formation

Unlike energy, entropy can never be zero (unless you are at 0K).