Question

For the reversible reaction,$ N_2 (g) + 3H_2 (g) \rightleftharpoons 2NH_3 (g) + heat$ the equilibrium shifts in forward direction

• A. by increasing the concentration of $ NH_3(g) $
• B. by decreasing the pressure
• C. by decreasing the concentrations of $ N_2 (g) $ and $ h_2 (g) $
• D. by increasing pressure and decreasing temperature

Answer 1

Answer: (D)

Any change in the concentration, pressure and temperature of the reaction results in change in the direction of equilibrium. This change in the direction of equilibrium is governed by
Le-Chatelier's principle. According to
Le-Chatelier's principle, equilibrium shifts in die opposite direction to undo the change.
$ N_2 (g) + 3H_2 (g) \rightleftharpoons 2Nh_3 (g) + Heat$
(a) Increasing the concentration of $ NH_3 (g): $
On increasing the concentration of $ NH_3 (g) $. the equilibrium shifts in the backward direction where concentration of $ NH_3 (g) $ decreases
(b) Decreasing the pressure: Since, $ p \propto n $ (number of moles), therefore, equilibrium shifts in the backward direction where number of moles are increasing.
(c) Decreasing the concentration of $ N_2 (g) $ and $ H_2 (g) $.
Equilibrium shifts in the backward direction when concentration of $ H_2 (g) $ and $ H_2 (g) $ decreases.
(d) Increasing pressure and decreasing temperature: On increasing pressure, equilibrium shifts in the forward direction where number of moles decreases. It is an example of exothermic reaction therefore decreasing temperature favours the forward direction