Question

For the reaction in equilibrium:
N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = -Q
Reaction is favoured in forward direction by:

• A. use of catalyst
• B. decreasing concentration of N₂
• C. low pressure, high temperature and high concentration of ammonia
• D. high pressure, low temperature and higher concentration of H₂

Answer 1

The Correct Option is D

Le Chatelier's principle states that a system at equilibrium subjected to a change in conditions will adjust to counteract that stress. For the exothermic reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g) (<strong>ΔH = -Q</strong>):

Increased Pressure: The forward reaction yields fewer gas moles (2 moles NH₃) compared to the reactants (4 moles N₂ and H₂). Higher pressure favors the side with fewer gas moles, thus promoting ammonia synthesis.

Reduced Temperature: As the reaction is exothermic, a lower temperature will favor the forward reaction (heat is considered a product).

Elevated Reactant Concentration: An increase in the concentration of N₂ or H₂ will drive the equilibrium to the right, consuming the added reactants.

A catalyst accelerates both forward and reverse reactions uniformly without altering the equilibrium position.