Question

Consider the equilibrium $N_2{O}_4\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)$, established from pure $N_2{O}_4\left(g\right)$, at a suitable temperature $T$. Keeping the temperature constant, the equilibrium is studied as a function of the total pressure $P$ of the gas mixture. Let $V$ be the volume of the gas mixture. For one mole as the initial amount of $N_2{O}_4\left(g\right)$, the correct plot (among $a,b,c,d$) in the given figure, assuming ideal gas behaviour, is:

• A. $a$
• B. $b$
• C. $c$
• D. $d$

Answer 1

The correct option is C $c$

Plot c represents the correct plot.
The number of moles of gaseous products is more than the number of moles of gaseous reactants. $\Delta n=2-1=+1$. Hence, when the pressure is increased, the equilibrium will shift towards left side which has fewer number of moles of gaseous species. This will minimize the impact of increase in pressure. Hence, with increase in pressure, the number of moles of $N_2{O}_4$ will increase first and then reach a maximum value.