How do the following changes affect the value of the equilibrium constant for a gas-phase exothermic reaction: (a) removal of a reactant, (b) removal of a product?

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

Verified step by step guidance

Step 1: Understand the nature of the equilibrium constant (K). The equilibrium constant is a ratio of the concentrations of products to reactants, each raised to the power of their stoichiometric coefficients, at equilibrium. It is only affected by changes in temperature.

Step 2: Recognize that the equilibrium constant (K) is not affected by changes in concentration, pressure, or volume. These changes can shift the position of equilibrium but do not change the value of K.

Step 3: Consider the effect of removing a reactant. According to Le Chatelier's Principle, removing a reactant will shift the equilibrium position to the left (toward the reactants) to counteract the change, but the value of K remains unchanged.

Step 4: Consider the effect of removing a product. Similarly, removing a product will shift the equilibrium position to the right (toward the products) to counteract the change, but again, the value of K remains unchanged.

Step 5: Conclude that for both scenarios (a) removal of a reactant and (b) removal of a product, the equilibrium constant (K) remains unchanged because K is only affected by temperature changes, not by changes in concentration of reactants or products.

Key Concepts

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

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. For a gas-phase reaction, K is determined by the partial pressures of the gases involved. It is important to note that K is only affected by changes in temperature, not by changes in concentration or pressure of reactants or products.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust itself to counteract the change and restore a new equilibrium. This principle helps predict how the removal of a reactant or product will shift the position of equilibrium, thereby affecting the concentrations of the remaining species without altering the equilibrium constant itself.

Exothermic Reactions

Exothermic reactions are chemical reactions that release heat to the surroundings, resulting in an increase in temperature. In the context of equilibrium, the heat released can be considered a product. For exothermic reactions, removing a product (heat) will shift the equilibrium to the right, favoring the formation of more products, while removing a reactant will shift it to the left, favoring the formation of reactants.

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Consider the reaction 4 NH₃(𝑔) + 5 O₂(𝑔) ⇌ 4 NO(𝑔) + 6 H₂O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (f) increase temperature.

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Textbook Question

Consider the reaction 4 NH₃(𝑔) + 5 O₂(𝑔) ⇌ 4 NO(𝑔) + 6 H₂O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (d) decrease the volume of the container in which the reaction occurs