Question

One mole of $N_2{O}_4$ at 300 K is kept in a closed container under one atmosphere. It is heated to 600K when $20\%$ by mass of $N_2{O}_4$ decomposes to $N{O}_2$ ( g ) . The resultant pressure is :

• A. 1.2 atm
• B. 2.4 atm
• C. 2.0 am
• D. 1.0 atm

Answer 1

The correct option is B 2.4 atm

The pressure at 300K is 1 atm.
Pressure at 600 K will be $P_2=T_2\times \frac{P_1}{T_1}=600\times \frac{1}{300}=2atm$.
Decomposition is 20% by mass of $N_2{O}_4$.

	$N_2{O}_4$	$N{O}_2$
Initial pressure	2	0
Change in pressure	-0.4	0.8
Equilibrium pressure	1.6	0.8

Total pressure $=1.6+0.8=2.4$.