The first step in industrial nitric acid production is the c

The first step in industrial nitric acid production is the catalyzed oxidation of ammonia. Without a catalyst, a different reaction predominates:
4NH₃(g) + 3O₂(g) ⇔ 2N₂(g) + 6H₂O(g)
When 0.0200 mol gaseous NH₃ and 0.0180 mol gaseous O₂ are placed in a 1.00 L container at a certain temperature, the N₂ concentration at equilibrium is 2.20×10^-3 M.
Calculate K_eq for the reaction at this temperature.

Solution

at equi [N2] = 2x = 0.0022, x = 0.0011,

[NH3] = 0.02-4(0.0011) = 0.0156, [O2] = ( 0.018)-3(0.0011) = 0.0147,

[H2O] = 6x = 6x0.0011 = 0.0066,

Keq = [H2O]^6[N2]^2/[O2]^3[NH3]^4

= ( 0.0066^6)(0.0022^2)/(0.0147^3)(0.0156^4)

= 2.12 x10^ -6