For the reaction 2NH3(g)↽−−⇀3H2(g)+N2(g)

Question

the equilibrium concentrations were found to be [NH3] =0.250 M, [H2] =0.420 M, and  [N2] =0.750 M.

What is the equilibrium constant for this reaction? Kc=______

Answer 1

First, write the equation for the reaction and balance it:

N₂ + 3H₂ ⇔ 2NH₃

This allows you to write an equilibrium expression specific to this reaction

The moles become exponents, and in general K_c = [products]/[reactants]

For this reaction, K_c = [NH₃]²/[H₂]³ [N₂]

Plug in the equilibrium concentrations given, so K_c = (0.250M)²/ (0.420M)³ x (0.750M)

K_c = 1.12