Question

One mole of N₂O₄ (g) at 300 K is kept in a closed container under one atmospheric pressure. It is heated to 600 K when 20% by mass of N₂O₄ (g) decomposes to NO₂ (g). The resultant pressure is

(a) 1.2 atm

(b) 2.4 atm

(c) 2.0 atm

(d) 1.0 atm

Answer 1

Correct option is (b) 2.4 atm

The pressure at 300K is 1 atm.

Pressure at 600 K will be \(P_2 = T_2 \times \frac{P_1}{T_1} = 600 \times \frac 1{300} = 2\ atm\).

Decomposition is 20% by mass of N₂O₄.

	N2O4	NO2
Initial pressure	2	0
Change in pressure	-0.4	0.8
Equilibrium pressure	1.6	0.8

Total pressure = 1.6 + 0.8 = 2.4.