Question

Consider the following reaction:

CO(g)+2H2(g)⇌CH3OH(g)CO(g)+2H2(g)⇌CH3OH(g)

The reaction between COCO and H2H2 is carried out at a specific temperature with initial concentrations of COCO = 0.32  M M and H2H2 = 0.52  M M. At equilibrium, the concentration of CH3OHCH3OH is 0.15  M M.

Find the equilibrium constant at this temperature.

Express your answer using two significant figures.

Answer 1

The given chemical reaction is-

CO(g) + 2H2(g) ⇌ CH3OH(g)

Now the equilibrium constant (K) of a reaction is the ratio between the product of concentrations of the products, each raised to the power of their number of moles involved,  to the product of concentrations of the reactants, each raised to the power of their number of moles involved , present at equilibrium.

i.e for the given reaction

K = [CH3OH(g)] / [CO(g)] * [H2(g)]²    where all the concentrations are only at the equilibrium

Now to calculate these concentrations at equilibrium, we have to form an ICE table as-

Reaction	CO(g) +	2H2(g) ------------->	CH3OH(g)
Initial	0.32  M	0.52  M	0 M
Change	-0.15  M	-2 * 0.15  M	+0.15  M
Equilibrium	0.17	0.22	0.15  M

So putting the values-

K = [CH3OH(g)] / [CO(g)] * [H2(g)]²

= [0.15] / [0.17] * [0.22]²

= 18.23

= 1.8 * 10¹