Question

Gaseous phosphorus pentachloride decomposes according to the reaction

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)

The equilibrium system was analyzed at a particular temperature, and the concentration of the substances present were determined to be [PCl5] = 1.1 x10-2 M, [PCl3] = 0.325 M, and [Cl2] = 3.9 x 10-3 M. Calculate the value of K for the reaction.

Answer 1

Step 1: Explanation

Kp is the equilibrium constant calculated from the partial pressures of a reaction equation. It is used to express the relationship between product pressures and reactant pressures

Step 2: Write the balanced the chemical equation

PCl₅ (g) <-----> PCl₃ (g) + Cl₂ (g)

All value at equilibrium is

[PCl₅] = 1.1 × 10^-2 M

[PCl₃] = 0.325 M

[Cl₂] = 3.9 × 10^-3 M

Step 3: Calculation of K_c

PCl₅ (g) <-----> PCl₃ (g) + Cl₂ (g)

we know, the K_c expression can be written as

Kc = [PCl₃] × [ Cl₂] / [PCl₅]

on substituting the values

=> Kc = [PCl₃] × [ Cl₂] / [PCl₅] = ( 0.325) × ( 3.9 × 10^-3 ) / ( 1.1 × 10^-2 ) = 0.11523

[ exact value of Kc= 0.1152272727 ]