Question

In 500ml flask the degree of dissociation of pcl5 at equilibrium is 40% and the initial amount is 5 moles. The value of equilibrium of pcl5 is

Answer 1

Answer : The value of equilibrium constant for dissociation of PCl5 is 2.67

Explanation :

The dissociation reaction of PCl5 can be written as,

$PCl_{5}\rightleftharpoons PCl_{3}+Cl_{2}$

Let us find the initial concentration of PCl5

[PCl5] = mol/L = 5 mol/0.500 L = 10 M

The degree of dissociation of PCl5 is 40%. That means 40% of the initial amount of PCl5 would dissociate to form the products.

40% of 10 M is 4 M.

This indicates that 4 M of PCl5 would dissociate to form 4 M of PCl3 and 4 M of Cl2.

Please refer to attached ICE table for the equilibrium concentrations of the above gases.

The equilibrium constant kc is calculated as,

$k_{c}=\frac{[PCl_{3}][Cl_{2}]}{[PCl_{5}]}$

Let us plug in the equilibrium values from the ICE table.

$k_{c}=\frac{(4M)(4M)}{(6M)}$

$k_{c}=\frac{16}{6}$

$k_{c}=2.67$

The value of equilibrium constant for dissociation of PCl5 is 2.67

Answer 2

Here is your answer!!!