At a particular temperature a 2.0 liter flask contains 2.0 mol of H2S, 0.40 mol of H2, and 0.80 mol of S2. Calculate the equilibrium constant for the reaction:

Question

2H2(g) + S2(g) <--> 2H2S(g)

Answer 1

I will assume that you want the equilibrium constant Kc, which is based upon concentrations [ ] in moles/liter. The coefficient Kp , based upon partial pressures in atm, could also be determined if the total pressure had been provided.

Kc = [H2S]^2/{[S2][H2]^2}
= 1.0^2/[0.4*(0.2)^2]
= 1/[(0.4)(0.04)] = 62.5 liter/mole