Question

Calculate the equilibrium constant (K_c) for the formation of NH₃ in the following reaction: 

\[\ce{N2(g) + 3H2(g) ⇌ 2NH3(g)}\]

At equilibrium, the concentration of NH₃, H₂ and N₂ are 1.2 × 10^-2, 3.0 × 10^-2 and 1.5 × 10^-2 M respectively.

Answer 1

N₂ + 3H₂ ⇌ 2NH₃ 

K_c = `(["NH"_3]^2)/(["N"_2]["H"_2]^3) = ((1.2 xx 10^-2)^2)/((1.5 xx 10^-2)(3 xx 10^-2)^3)`

`= (1.2 xx 1.2 xx 10^-4)/(1.5 xx 10^-2 xx 3 xx 3 xx 3 xx 10^-6) = (1.2 xx 1.2 xx 10^4)/(1.5 xx 9 xx 3)`

`= (1.44 xx 10^4)/(1.5 xx 9 xx 3) = 400`