Consider the reaction

Question

CO(g) + H2O(g) <--> CO2(g) + H2(g)

Use the appropriate tables to calculate
a) delta-G*f at 552*C
b) K at 552*C

I'm pretty sure I have a good idea of how to do this: I believe I can use Gibbs-Helmholtz equation to account for the temperatures... however, what I have a question on is this:
1. Can the Gibbs-Helmholtz equation be used for delta-G*f?
2. How would I use this if I have 2 reactants?

delta G^o poducts - delta G^o reactants = delta G^o rxn.
delta G = delta G^o + RTln Q.
At equilibrium, delta G = 0 and ln Q = ln K, so
delta G^o = -RT ln K.