Choose the CORRECT expression for equilibrium constant, K, of the following reaction at constant temperature and pressure. 3 Fe(s) + 4 H2O(g) « Fe3O4(s) + 4 H2 (g)


A.K = [Fe3O4][H2]4 / [Fe]3[H2O]4B.K = [Fe3O4][H2]4 / [H2O]4C.K = [H2]4 / [Fe]3[H2O]4D.K = [H2]4 / [H2O]4E.K = [Fe3O4] / [Fe]3
I cant understand why its not a?? the explanation says that Fe..etc are pure solids are constant values encorporated into Keq? It just doesn't make sense to me.. :(
Thanks :)

Its not A because you dont include solids in the expression.

than you for the reply=) but the explanation says pure solids or liquids? I would think water is a pure liquid? Or does it mean that if it's composed with more than 1 atom, it's not pure anymore?

it says H2O(g) so it's a gas for that reaction.

than you for the reply=) but the explanation says pure solids or liquids? I would think water is a pure liquid? Or does it mean that if it's composed with more than 1 atom, it's not pure anymore?


Yea, H2O is listed as a gas in that expression...hehe

i believe when calculating equilibrium YOU DONT USE SOLIDs (s)

The concentrations of liquids and solids do not change, therefore they can be left out of the equilibrium equation.

thanks everyone! Now i get it :) For some reason, equillibrium is my worst topic.. even though i know it should be easy!!!