Question

Identify the reaction which proceeds at low pressure?

• A. $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$
• B. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)$
• C. $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
• D. $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$

Answer 1

The correct option is A $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$

According to the Le chatelier's principle at low pressure, reaction will proceed to the direction which has more no. of moles. The number of moles in product side should greater than the reactants side. This is favourable only for the reaction, $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$.
So, that reaction will proceed at low pressure.