For the reaction in equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g), ΔH = -Q

Question

For the reaction in equilibrium

\(N_2 (g) + 3H_2 (g) \rightleftharpoons 2NH_3 (g) , \triangle H = - Q\)

Reaction is favoured in forward direction by: 

(1) use of catalyst 

(2) decreasing concentration of \(N_2 \)

(3) low pressure, high temperature and high concentration of ammonia 

(4) high pressure, low temperature and higher concentration of \(H_2\)

Answer 1

Correct option is (4) high pressure, low temperature and higher concentration of \(H_2\)

\(N_2 (g) + 3H_2 (g) \rightleftharpoons 2NH_3 (g) , \triangle H = - Q\)

According to Le Chatelier’s principle. 

• Exothermic reactions are favoured at low temperature. 

• Increase in pressure shifts the reaction in direction having lesser number of moles. Hence, the given reaction shifts forward on increasing pressure. 

• Increasing the concentration of reactants shifts the reaction in forward direction. So high concentration of \(H_2\) shifts reaction in forward direction.