Question

Calculate the equilibrium constant for the following reaction: 2NaO(g) ⇌ Na2O2(g)

Given: NaO(g) ⇌ Na(l) + 1/2O2 K = 2 x 10-5

Na2O2 ⇌ 2Na(l) + O2(g) K = 5 x 10-29

Answer 1

Three important points to recall are

1. When the equation is multiplied by a factor of n, the new equilibrium expression can

be written as K_new=(K_orig)ⁿ

2. The equilibrium expression for a reaction written in the reverse is the reciprocal of that

for the original reaction.

3. For a reaction made up of two or more steps, the equilibrium constant for the net reaction is the product of the equilibrium constants of the individual steps

The required equilibrium equation is obtained by adopting following steps.

[equation(1) x 2 ] + [reverse of equation(2)]

so equilibrium constant of the resultant equation = K₁² / K₂

= {( 2 x 10^-5)² } / [ 5 x 10^-29] = 0.8 x 10¹⁹ = 8 x 10¹⁸