At 35ºC, the equilibrium constant for the reaction 2NOCl(g) 2NO(g) + Cl₂(g) is K = 1.6 × 10⁻⁵.An equilibrium mixture was found to have the following concentrations of Cl₂ and NOCl: [Cl₂] = 1.2 × 10⁻² M; [NOCl] = 2.8 × 10⁻¹ M.Calculate the concentration of NO(g) at equilibrium.

Question

Quizplus · Accepted Answer

First, we need to write the balanced chemical equation and the expression for the equilibrium constant:

2NOCl(g) ⇌ 2NO(g) + Cl2(g)
K = [NO]2[Cl2]/[NOCl]2

We are given the concentrations of NOCl and Cl2 at equilibrium, but not the concentration of NO. To solve for [NO], we need to use the equilibrium constant and the concentrations of the other species:

K = [NO]2[Cl2]/[NOCl]2
1.6 × 10^-5 = (2x)^2(1.2x)/(2.8x)^2

Simplifying and solving for x gives:

x = 1.0 × 10^-2 M

Therefore, the concentration of NO at equilibrium is 1.0 × 10^-2 M, which is answer choice B.

At 35ºC, the Equilibrium Constant for the Reaction 2NOCl(g)