### Solving Gibbs Free Energy Problems

Posted:

**Sat Feb 29, 2020 6:43 pm**For questions like 5G.15,

(a) Calculate the reaction Gibbs free energy of N2(g) + 3 H2(g) -> 2 NH3(g) when the partial pressures of N2, H2, and NH3 are 4.2 bar, 1.8 bar, and 21 bar, respectively, and the temperature is 400. K. For this reaction, K = 41 at 400. K. (b) Indicate whether this reaction mixture is likely to form reactants, is likely to form products, or is at equilibrium.

do we use the equation ΔGr = -RTlnK + RTlnQ only because K is given? If K isn't given, how would we solve this problem with ΔGr = ΔGr° + RTlnQ?

I feel like I forgot how to solve these problems after haven't done them in a while :(

(a) Calculate the reaction Gibbs free energy of N2(g) + 3 H2(g) -> 2 NH3(g) when the partial pressures of N2, H2, and NH3 are 4.2 bar, 1.8 bar, and 21 bar, respectively, and the temperature is 400. K. For this reaction, K = 41 at 400. K. (b) Indicate whether this reaction mixture is likely to form reactants, is likely to form products, or is at equilibrium.

do we use the equation ΔGr = -RTlnK + RTlnQ only because K is given? If K isn't given, how would we solve this problem with ΔGr = ΔGr° + RTlnQ?

I feel like I forgot how to solve these problems after haven't done them in a while :(