Problem 36 - A Complete Resource Book in Chemistry for JEE Main

Question

For the chemical reaction \(3 \mathrm{X}(\mathrm{g})+\mathrm{Y}(\mathrm{g}) \rightleftharpoons \mathrm{X}_{3} \mathrm{Y}(\mathrm{g})\), the amount of \(\mathrm{X}_{3} \mathrm{Y}\) at equilibrium is affected by (a) temperature and pressure (b) temperature only (c) pressure only (d) temperature, pressure and catalyst

Step-by-Step Solution

Answer

(a) temperature and pressure

Step 1: Understand the Reaction

The balanced chemical equation is \(3X(g) + Y(g) \rightleftharpoons X_3Y(g)\). This is a gaseous system at equilibrium, which means changes in temperature and pressure can influence the equilibrium position.

Step 2: Analyze the Effect of Pressure

Using Le Chatelier's Principle, an increase in pressure will shift the equilibrium towards the side with fewer moles of gas to decrease pressure. Here, we have 4 moles of reactants and 1 mole of product. Therefore, increasing pressure favors the formation of \(X_3Y(g)\).

Step 3: Analyze the Effect of Temperature

The effect of temperature depends on whether the reaction is exothermic or endothermic. Without specific information on the reaction's enthalpy, we can conclude that temperature changes affect equilibrium position, impacting \([X_3Y]\) under such conditions.

Step 4: Analyze the Effect of a Catalyst

A catalyst speeds up the rate at which equilibrium is achieved but does not affect the position of equilibrium. Therefore, a catalyst will not change the amount of \(X_3Y\) at equilibrium but will affect how quickly equilibrium is reached.

Step 5: Conclude the Solution

Therefore, the formation of \(X_3Y(g)\) is affected by both temperature and pressure. A catalyst does not alter the equilibrium position.

Key Concepts

Chemical Equilibrium

Chemical equilibrium refers to the state of a reversible reaction where the forward and backward reactions occur at the same rate. During this state, the concentrations of reactants and products remain constant, but not necessarily equal. This is not a static state; rather, it is dynamic where bonds are constantly being formed and broken.In the reaction given, \[ 3X(g) + Y(g) \rightleftharpoons X_3Y(g) \]chemical equilibrium is achieved when the rate of formation of \(X_3Y(g)\) from \(X(g)\) and \(Y(g)\) is equal to the rate of its decomposition back into \(X(g)\) and \(Y(g)\). At equilibrium, any changes in concentration, temperature, or pressure will alter the system, and Le Chatelier's Principle can be used to predict these changes.

Effect of Temperature

Temperature is a critical factor in affecting chemical equilibrium. Its effect depends on whether the reaction is exothermic or endothermic:- **Exothermic Reactions:** If you increase the temperature, the equilibrium will shift towards the reactants, as the system tries to absorb the extra heat. Lowering the temperature favors the exothermic direction, producing more products.- **Endothermic Reactions:** Increasing the temperature favors the forward direction, producing more products, as the system absorbs heat. Decreasing the temperature will shift the equilibrium towards the reactants.For the reaction \[ 3X(g) + Y(g) \rightleftharpoons X_3Y(g) \]without specific enthalpy data, we can only confirm that temperature changes will alter the equilibrium position.Overall, adjusting the reaction temperature can significantly change the amount of \(X_3Y(g)\) present at equilibrium.

Effect of Pressure

In gas-phase reactions, like the one involving \[ 3X(g) + Y(g) \rightleftharpoons X_3Y(g) \]the pressure can greatly influence the position of equilibrium, especially when there is a difference in the number of moles of gas on either side of the equation.- **Increase in Pressure:** According to Le Chatelier's Principle, increasing pressure will shift the equilibrium towards the side with fewer moles of gas. In this case, going from 4 moles of reactants (3 moles of \(X\) and 1 mole of \(Y\)) to 1 mole of \(X_3Y\), increased pressure will favor the formation of \(X_3Y(g)\).- **Decrease in Pressure:** Decreasing pressure will shift the equilibrium towards the side with more moles of gas, favoring the reactants.Therefore, pressure changes can notably affect how much of the product is present at equilibrium by shifting the reaction towards one side or the other.