Question

20mol NOCl is placed in a 4L container,

At equilibrium, 8mol of Cl was found to be in the container. Calculate the value of kc for the reaction NOCl=N2 + Cl2

Answer 1

The balanced chemical equation for the reaction is:

2 NOCl ⇌ N2 + Cl2

The equilibrium constant expression for this reaction is:

Kc = [N2][Cl2]/[NOCl]^2

We are given that 20 mol of NOCl is placed in a 4 L container, which means that the initial concentration of NOCl is:

[NOCl] = 20 mol/4 L = 5 mol/L

At equilibrium, 8 mol of Cl2 is found in the container. Since the reaction stoichiometry tells us that 2 mol of NOCl produces 1 mol of Cl2, we can calculate the equilibrium concentration of Cl2:

[Cl2] = 8 mol/(4 L x 2) = 1 mol/L

Using the equilibrium concentrations of NOCl and Cl2, we can calculate the equilibrium concentration of N2 using the stoichiometry of the reaction:

[N2] = [NOCl]/2 = 5 mol/L / 2 = 2.5 mol/L

Substituting these equilibrium concentrations into the equilibrium constant expression gives:

Kc = [N2][Cl2]/[NOCl]^2
Kc = (2.5 mol/L)(1 mol/L)/(5 mol/L)^2
Kc = 0.1 L/mol

Therefore, the value of Kc for the reaction is 0.1 L/mol.