Which of the following best describes the difference between the rate of a reaction and its rate constant?

• A. The rate constant changes during the reaction, while the rate of a reaction remains constant.
• B. The rate of a reaction depends on the concentrations of reactants, while the rate constant is independent of concentration and depends only on temperature.
• C. Both the rate of a reaction and its rate constant depend on the concentrations of reactants.
• D. The rate of a reaction is always greater than the rate constant.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definition of the rate of a reaction. The rate of a reaction is the change in concentration of a reactant or product per unit time, and it depends on the concentrations of the reactants involved in the reaction at a given moment.
2. Step 2: Understand the definition of the rate constant (k). The rate constant is a proportionality constant in the rate law that relates the reaction rate to the concentrations of reactants raised to their respective orders. It is specific to a particular reaction at a given temperature.
3. Step 3: Recognize that the rate constant is independent of reactant concentrations. Instead, it depends primarily on temperature and the presence of a catalyst, remaining constant during the reaction if these conditions do not change.
4. Step 4: Note that the rate of reaction changes as the concentrations of reactants change over time, while the rate constant remains unchanged under constant temperature conditions.
5. Step 5: Summarize the key difference: The rate of a reaction depends on the concentrations of reactants and changes as the reaction proceeds, whereas the rate constant is a fixed value for a given reaction at a specific temperature and does not depend on reactant concentrations.