The following pictures represent the initial and equilibrium states for the exothermic decomposition of gaseous A mol- ecules (red) to give gaseous B molecules (blue).(b) Will the number of A molecules in the equilibrium mix- ture increase, decrease, or remain the same after each of the following changes? Explain.(3) Increasing the pressure by adding an inert gas

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Identify the reaction: The problem involves the exothermic decomposition of gaseous A molecules into gaseous B molecules.

Understand the effect of adding an inert gas: Adding an inert gas at constant volume does not change the partial pressures of the reacting gases, as it does not participate in the reaction.

Apply Le Chatelier's Principle: Since the inert gas does not affect the partial pressures of A or B, the equilibrium position is not shifted by the addition of the inert gas.

Consider the number of moles: The total pressure increases, but the partial pressures of A and B remain unchanged, so the equilibrium concentrations of A and B remain the same.

Conclude: The number of A molecules in the equilibrium mixture will remain the same after adding an inert gas.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change. In the context of gaseous reactions, this principle helps predict how changes in pressure, temperature, or concentration will affect the equilibrium state.

Effect of Inert Gases on Equilibrium

Adding an inert gas at constant volume does not change the partial pressures of the reactants or products in a reaction at equilibrium. Since the inert gas does not participate in the reaction, it does not affect the equilibrium position directly, but it can influence the total pressure of the system.

Exothermic Reactions and Equilibrium

In exothermic reactions, heat is released as a product. When considering changes in temperature or pressure, the equilibrium will shift in a direction that either absorbs heat (endothermic) or releases heat (exothermic) to maintain balance. Understanding this helps predict how the equilibrium will respond to changes in conditions.

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Identify the true statement about the rate of the forward and reverse reaction once a reaction has reached equilibrium. (a) The rate of the forward reaction and the reverse reaction is zero. (b) The rate of the forward reaction is greater than the rate of the reverse reaction. (c) The rate of the reverse reaction is greater than the rate of the forward reaction. (d) The rate of the forward reaction is equal to the rate of the reverse reaction.