Question

Which of the following will shift the reaction ${PCl}_3\left(g\right)+{Cl}_2\left(g\right)\rightleftharpoons {PCl}_5\left(g\right),\Delta H=(+)ve$ to left hand side?

• A. Addition of ${PCl}_5$
• B. Increase in pressure
• C. Increase in temperature
• D. Catalyst

Answer 1

Answer: (A), (D)

The correct options are
A Addition of ${PCl}_5$
D Catalyst

According to Le-Chatelier's principle , an increase in the concentration of product favours backward reaction. Therefore, addition of $PC{l}_5$ will shift reaction to left hand side.

An increase in pressure will shift the reaction to right hand side as the number of moles products is less. It is an endothermic reaction, therefore, an increase in temperature favours forward reaction that is to the right hand side.

A catalyst can be used to shift the reaction to the left hand side.