Question

For a chemical reaction with rise in temperature by \(10^\circ C\) the rate constant is nearly:

• A. No change
• B. Tripled
• C. Doubled
• D. Ten time increases

Hint:

This is an approximate rule; actual increase depends on activation energy of the reaction.

Answer 1

The Correct Option is C

Concept: The effect of temperature on reaction rate is explained by the Arrhenius equation. A general empirical rule in chemical kinetics states:
Van’t Hoff Rule: For many reactions, the rate of reaction approximately doubles for every \(10^\circ C\) rise in temperature. \[ k \propto e^{-E_a/RT} \] An increase in temperature increases the number of molecules having energy greater than activation energy, thus increasing the rate constant.
Explanation:
Higher temperature → more energetic molecular collisions.
Greater fraction of molecules overcome activation energy.
Rate constant increases significantly.
Empirically: \[ \text{Increase of } 10^\circ C \Rightarrow \text{Rate } \approx 2 \times \] \[ \boxed{\text{Rate constant nearly doubles}} \]