Which of the following statements correctly describes the effect of a catalyst on a chemical reaction?

• A. A catalyst increases the rate of reaction by lowering the activation energy, but does not change the equilibrium position.
• B. A catalyst increases both the rate of reaction and shifts the equilibrium toward the products.
• C. A catalyst decreases the rate of reaction and increases the activation energy.
• D. A catalyst increases the rate of reaction by increasing the temperature of the system.

Answer: (A)

Verified step by step guidance

1. Understand that a catalyst is a substance that speeds up a chemical reaction without being consumed in the process.
2. Recall that the catalyst works by providing an alternative reaction pathway with a lower activation energy, which increases the rate at which reactants convert to products.
3. Recognize that while a catalyst affects the rate of both the forward and reverse reactions equally, it does not affect the position of the chemical equilibrium; the equilibrium constant remains unchanged.
4. Eliminate options that suggest the catalyst changes the equilibrium position or increases the temperature, as catalysts do not alter thermodynamic properties or system temperature.
5. Conclude that the correct description is: a catalyst increases the rate of reaction by lowering the activation energy but does not change the equilibrium position.