Question

For N₂O₄ ⇋ 2NO₂, NO₂ is 50% of the total volume at equilibrium in 1 L flask. Hence starting with 1 mol of N₂O₄ at constant temperature, equilibrium constant K_c is

(A) 0.66 

(B) 0.33 

(C) 1.00

(D) none of these

Answer 1

Correct option (A) 0.66 

Explanation : 

Total mole at equilibrium = (1 + x)

Answer 2

ICE TABLE

                                           N₂O₄            ⇋          2NO₂

Initial                                    1 mol                         0                            

change                                  x                              2x

Equilibrium.                           1-x                              2x                            

Mole fraction of NO₂ = 2x/(1-x+2x) => 2x/(x+1) = ½

[since NO₂ is 50% of the total volume ]

 solving we get, 4x = x+1

3x = 1

x = 1/3

Since volume of the vessel is 1L

The concentration equilibrium constant

K_c = > (2x)^2/(1-x) = (2/3)^2/(1-1/3) =(4/9)/(2/3) = 4*3/9*2 = 2/3=0.66

Option A