Considering the following reaction: CO(g) + 2 H2(g) --> CH3OH(g) Suppose that the initial concentrations of the reactants are [CO] = 0.500 M and [H2] = 1.00 M. Assuming that there is no product at the beginning of the reaction and that at equilibrium [CO] = 0.15 M, what is the equilibrium constant at this new temperature?

1 Answer
Sep 14, 2014

The equilibrium constant is 26.

First, write the balanced chemical equation with an ICE table.

CO(g) + 2H₂(g) ⇌ CH₃OH(g)

I/mol·L⁻¹: 0.500; 0.100; 0
C/mol·L⁻¹: -x; -2x; +x
E/mol·L⁻¹: 0.500 - x; 0.100 - 2x; x

At equilibrium, [CO] = 0.15 mol/L = (0.500 - x) mol/L

So x = 0.500 – 0.15 = 0.35

Then [H2] = (0.100 - 2x) mol/L = (0.100 – 2×0.35) mol/L = 0.30 mol/L

and

[CH3OH] = x mol/L = 0.35 mol/L

Keq=[CH3OH][CO][H2]2=0.350.15×0.302 = 26