A sample of pure PCl 5 was introduced into an evacuated vessel at 473 K. After equilibrium was attained, concentration of PCl5 was found to be 0.5 × 10 –1 mol L –1 . If value of K c is 8.3 × 10 –3 , what are the concentrations of PCl 3 and Cl 2 at equilibrium? PCl 5 (g) ⇌ PCl 3 (g) + Cl 2 (g)

Question

Philoid · Accepted Answer

For the given reaction, let’s assume that the initial molar concentration of PCl₅ is x mol/L.

The given reaction is:

Moles of PCl₅ decomposed during the reaction=Moles of PCl₃ formed=Moles of Cl₂ formed=(x-0.05) mol/L

Equilibrium constant (K_c) is defined as a number that expresses the relationship between the amounts of products and reactants present at equilibrium in a reversible chemical reaction at a given temperature.

Here, K_c = 0.0083

For the given reaction,

Where, [PCl₃] = concentration of PCl₃ in mol/L at equilibrium

[Cl₂] = concentration of Cl₂ in mol/L at equilibrium

[PCl₅] = concentration of PCl₅ in mol/L at equilibrium

(x-0.05)² = 0.000415

(x-0.05) = 0.0203

x = 0.07 mol/L

Therefore, [PCl₃] = (x-0.05) = 0.07-0.05 = 0.02 mol/L

[Cl₂] = (x-0.05) = 0.07-0.05 = 0.02 mol/L

A sample of pure PCl5 was introduced into an evacuated vessel at 473 K. After equilibrium was attained, concentration of PCl5 was found to be 0.5 × 10–1 mol L–1. If value of Kc is 8.3 × 10–3, what are the concentrations of PCl3 and Cl2 at equilibrium?PCl5 (g) ⇌ PCl3 (g) + Cl2(g)