## stoichiometric coefficients for calculating Gibbs free energy

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

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

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

Sarah Kiamanesh 1D
Posts: 30
Joined: Fri Sep 28, 2018 12:22 am

### stoichiometric coefficients for calculating Gibbs free energy

I understand that in some equations like the formation of NH3 (N2 + 3H2 --> 2NH3), the coefficients are all divided by two to produce 1/2N2 + 3/2H2 --> NH3, while other equations keep their original coefficients. what's the procedure for this? when do we need to do this? does it make a difference?

melodyzaki2E
Posts: 61
Joined: Fri Sep 28, 2018 12:18 am

### Re: stoichiometric coefficients for calculating Gibbs free energy

I think this is when you are calculating the enthalpy of formation of the standard molar entropy for 1 mole of NH3 because then you just want to produce one mole of that product. I'm not totally sure though.

Kim Tran 1J
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

### Re: stoichiometric coefficients for calculating Gibbs free energy

Unless stated otherwise in the problem, I think you are to assume the problem is asking for the change in Gibbs Free Energy for the creation of one mole of product hence why it would be 1/2N2 + 3/2H2 --> NH3 and not N2 + 3H2 --> 2NH3.