Question

One mole of $N_2{O}_4$ gas at $300K$ is kept in a closed container at $1$atm. It is heated to $600K$ when $20$% by mass of $N_2{O}_4$ decomposes to ${NO}_{2\left(g\right)}$. The resultant pressure in the container would be

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

Answer 1

Answer: (B)

$2.4$ atm

$N_2{O}_4\left(g\right)\rightleftharpoons 2NO\left(g\right)$
Initial no. of moles $1$ $0$
No. of moles at equi. $(1-0.2)$ $0.4$
total number of moles at equilibrium $=1.2$
Initially $P_{1}V=n_{1}RT$
or $1\times V=1\times RT$
or $V=R{T}_1$
At equilibrium $P_{2}V=n_{2}R{T}_2$
$P_2=\frac{1.2}{V}R{T}_2=\frac{1.2}{R{T}_1}R{T}_2=\frac{1.2\times 600=}{300}2.4atm$