Question

Which one of the following conditions will favour maximum formation of the product in the reaction,
A₂(g) + B₂(g) ⇌ X₂(g) Δ_rH = – X kJ ?

• A. Low temperature and high pressure
• B. High temperature and high pressure
• C. Low temperature and low pressure
• D. High temperature and low pressure

Answer 1

The Correct Option is A

To determine the conditions that will favor the maximum formation of the product in the reaction:

\( A_2(g) + B_2(g) \rightleftharpoons X_2(g) \) with \( \Delta_r H = -X \, \text{kJ} \), we need to consider the principles of thermodynamics and equilibrium.

1. Since the reaction is exothermic (as indicated by the negative enthalpy change \( \Delta_r H \)), the formation of products will be favored at low temperatures according to Le Chatelier's principle. Lowering the temperature shifts the equilibrium position to the right in an exothermic reaction, favoring product formation.
2. The reaction involves gases, and by applying Le Chatelier's principle concerning pressure, increased pressure will favor the side of the reaction with fewer moles of gas. Here, the number of moles on both sides is the same (\( 1 \) mole each for reactants and products). However, increased pressure generally helps in reactions where the gas phase is involved and should be considered as beneficial for shifting equilibrium under these conditions.

Based on these principles, the conditions that will favor the maximum formation of the product \( X_2(g) \) are:

• Low Temperature: Favors the exothermic production of the product.
• High Pressure: Applies generally to equilibrium reactions involving gases.

Therefore, the correct answer is "Low temperature and high pressure".