Question

In which of the following systems, doubling the volume of the container causes a shift to right?

• A. $H_2\left(g\right)+I_2\left(g\right)\leftrightharpoons 2HI\left(g\right)$
• B. $2CO\left(g\right)+O_2\left(g\right)\leftrightharpoons 2C{O}_2\left(g\right)$
• C. $N_2\left(g\right)+3H_2\left(g\right)\leftrightharpoons 2N{H}_3\left(g\right)$
• D. $PC{l}_5\left(g\right)\leftrightharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$

Answer 1

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

When the volume of the container is doubled, its pressure is reduced to half. The equilibrium will shift in a direction so that the total number of moles will increase. This is in accordance with Le Chatelier's principle.

This will increase the pressure. When the number of moles of products is greater than the number of moles of reactants, the shift in equilibrium towards the right will increase the number of moles.

This is true for the decomposition of phosphorus pentachloride to form phosphorus trichloride and chlorine. Hence, the equilibrium for the reaction in option D will shift towards the right, as the volume of the container is doubled.