True or false: When the temperature of an exothermic reaction increases, the rate constant of the forward reaction decreases, which leads to a decrease in the equilibrium constant, Kc.

Verified step by step guidance

Understand the nature of exothermic reactions: In an exothermic reaction, heat is released as a product. This means that increasing the temperature adds more heat to the system.

Apply Le Chatelier's Principle: When the temperature of an exothermic reaction is increased, the system will shift to counteract this change by favoring the endothermic direction, which is the reverse reaction.

Consider the effect on the rate constant: The rate constant for a reaction is affected by temperature according to the Arrhenius equation. Generally, increasing temperature increases the rate constant for both forward and reverse reactions, but the reverse reaction is favored in this case.

Analyze the impact on the equilibrium constant, Kc: The equilibrium constant, Kc, is dependent on temperature. For an exothermic reaction, increasing the temperature will decrease Kc because the equilibrium shifts towards the reactants.

Conclude the statement: The statement is false because while the rate constant for the forward reaction may decrease relative to the reverse reaction, the equilibrium constant, Kc, decreases due to the shift in equilibrium position, not because of a decrease in the forward rate constant alone.

Key Concepts

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

Exothermic Reactions

Exothermic reactions are chemical processes that release energy, usually in the form of heat, to the surroundings. This release of energy results in a temperature increase in the surrounding environment. The enthalpy change (ΔH) for exothermic reactions is negative, indicating that the products have lower energy than the reactants.

Rate Constant and Temperature

The rate constant (k) of a reaction is influenced by temperature, as described by the Arrhenius equation. Generally, an increase in temperature leads to an increase in the rate constant for both forward and reverse reactions, enhancing the reaction rate. However, for exothermic reactions, the relationship between temperature and the rate constant can be complex due to the effects on equilibrium.

Equilibrium Constant (Kc)

The equilibrium constant (Kc) is a ratio that expresses the concentrations of products to reactants at equilibrium for a reversible reaction. For exothermic reactions, an increase in temperature typically shifts the equilibrium position to favor reactants, resulting in a decrease in Kc. This is consistent with Le Chatelier's principle, which states that a system at equilibrium will adjust to counteract changes in conditions.

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Textbook Question

The following diagram represents a reaction shown going to completion. Each molecule in the diagram represents 0.1 mol, and the volume of the box is 1.0 L. (d) Assuming that all of the molecules are in the gas phase, calculate n, the change in the number of gas molecules that accompanies the reaction. [Section 15.2]

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Textbook Question

Ethene (C₂H₄) reacts with halogens (X₂) by the following reaction:

C₂H₄(𝑔) + X₂(𝑔) ⇌ C₂H₄X₂(𝑔)

The following figures represent the concentrations at equilibrium at the same temperature when X₂ is Cl₂ (green), Br₂ (brown), and I₂ (purple). List the equilibria from smallest to largest equilibrium constant. [Section 15.3]

Textbook Question

When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO2(𝑠) ⇌ 2PbO(𝑠) + O2(𝑔). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true? a. There will be less PbO₂remaining in vessel A,

Textbook Question

When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO₂(𝑠)⇌2PbO(𝑠)+O2(𝑔). Consider the two sealed vessels of PbO₂ shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true?

b. There will be less PbO₂ remaining in vessel B,

Textbook Question

When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO₂(𝑠) ⇌ 2PbO(𝑠) + O₂(𝑔). Consider the two sealed vessels of PbO₂ shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true? (c) The amount of PbO₂ remaining in each vessel will be the same. [Find more in Section 15.4]