Question

In a 400 ml of flask the initial amount of pcl5 4 moles and at equilibrium the
degree of dissociation is 50% The value of equilibrium constantin moIL5
is​

Answer 1

Given info : In a 400 ml of flask the initial amount of PCl₅, 4 moles and at equilibrium the degree of dissociation is 50%.

To find : The value of equilibrium constant is ...

solution : dissociation reaction of PCl₅ is ..

PCl₅ ⇒PCl₃ + Cl₂

at t = 0. x 0 0

at eql x(1 - α) xα xα

here , x = no of moles of reactants/volume

= 4/(400/1000) mol/L

= 10 mol/L

degree of dissociation, α = 50 % = 0.5 ( in fraction)

now equilibrium constant, K = [PCl₃][Cl₂]/[PCl₅]

= (xα × xα)/x(1 - α)

= xα²/(1 - α)

= 10 × (0.5)²/(1 - 0.5)

= 10 × 0.5

= 5

Therefore the equilibrium constant of given reaction is 5