Question

When a catalyst increases the rate of a chemical reaction, the rate constant:

• A. increases
• B. decreases
• C. remains constant
• D. becomes infinite

Answer 1

Answer: (A)

increases

A catalyst increases the rate of a reaction by decreasing the activation $\left(E_a\right)$ energy needed for the reactions.

According to Arrhenius equation

$k=A{e}^{-E_a/RT}$

When $E_a$ decreases, $\left({-E}_a/RT\right)$ increases.

this causes $e^{-E_a/RT}$ to increase, and thus rate constant k increases.