Question

Which one of the following conditions will favour maximum formation of the product in the reaction, \( A_{2}(g) + B_{2}(g) \rightleftharpoons X_{2}(g) \), \( \Delta_r H = -x \,\text{kJ} \):

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

Hint:

Think of pressure as a "space-saver": High pressure pushes the reaction toward whichever side takes up less "space" (fewer gas moles). For temperature, think of heat as a product in exothermic reactions; adding more "product" (heat) pushes the reaction backward.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
According to Le Chatelier's Principle, if a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the system will shift its equilibrium position to counteract the effect of the change.

Step 2: Detailed Explanation
1. Effect of Temperature: The reaction is exothermic (\( \Delta H = -x \) kJ). Increasing temperature favors the endothermic (backward) direction. Therefore, low temperature is required to favor the forward reaction (product formation).
2. Effect of Pressure: Look at the number of moles of gas: - Reactants: \( 1 + 1 = 2 \) moles. - Products: 1 mole. An increase in pressure shifts the equilibrium toward the side with fewer moles of gas. Since the product side has 1 mole compared to 2 moles of reactants, high pressure will favor product formation.

Step 3: Final Answer
The reaction is favored by low temperature and high pressure.