Question

A catalyst increases the rate of reaction by:

• A. Increasing activation energy
• B. Decreasing activation energy
• C. Changing the equilibrium constant
• D. Increasing temperature

Hint:

A catalyst accelerates a reaction by lowering the energy barrier — it helps more molecules achieve the activation energy threshold.

Answer 1

The Correct Option is B

A catalyst is a substance that increases the rate of a chemical reaction without itself being consumed in the process.
It achieves this by providing an alternative reaction pathway that has a lower activation energy ($E_a$).
According to the Arrhenius equation:
\[ k = A e^{-E_a/RT} \]
A lower activation energy increases the rate constant $k$, and thereby increases the reaction rate.
Important points to note:
- A catalyst does not change the equilibrium constant; it only helps the system reach equilibrium faster.
- Increasing temperature can also increase reaction rate, but that is not the role of a catalyst.
- Increasing activation energy would decrease the rate, which is the opposite effect of a catalyst.
Thus, the correct mechanism by which a catalyst works is by decreasing activation energy.