Question

Formation of ammonia will be favorable in the following cases(s):
$N_2\left(g\right)+3H_2\left(g\right)\to 2N{H}_3\left(g\right)$ $\Delta H<0$

• A. Addition of inert gas at constant volume
• B. Decreasing the volume of the container
• C. Addition of inert gas at constant pressure
• D. Increasing the pressure

Answer 1

Answer: (D)

Increasing the pressure

• In accordance with Le Chatelier’s principle, high pressure would favour the formation of ammonia. The optimum conditions for the production of ammonia are a pressure of 200 × 105 Pa (about 200 atm), a temperature of ~ 700 K and the use of a catalyst such as iron oxide with small amounts of $K_{2}O$ and $A{l}_2{O}_3$ to increase the rate of attainment of equilibrium.
  
• Addition of an inert gas at constant volume: When an inert gas is added to the system in equilibrium at constant volume, the total pressure will increase. But the concentrations of the products and reactants (i.e. ratio of their moles to the volume of the container) will not change.
  
• Hence, option A is correct answer as addition of ideal gas increases pressure and thus favours formation of Ammonia.