Question

the rate law for the reaction represented above is experimentally determined to be rate = kn₂o. which of the following best explains why increasing the initial concentration of n₂o(g) at a constant temperature increases the reaction rate? a molecular collisions become more frequent. b there is a higher probability of effective molecular collisions. c the rate constant for the reaction increases. d the reaction mechanism changes to one that has a lower activation energy.

Explanation:

• Option A: Increasing reactant concentration (here, $\ce{N_{2}O}$) means more molecules per unit volume. So, molecular collisions become more frequent, increasing the reaction rate.
• Option B: The probability of effective collisions (which depends on orientation and energy) doesn't increase with concentration alone; only the frequency of collisions does.
• Option C: The rate constant $k$ depends on temperature (and catalysts), not concentration. So, $k$ doesn't increase with $\ce{N_{2}O}$ concentration.
• Option D: Changing the initial concentration of a reactant doesn't alter the reaction mechanism or activation energy. Activation energy is a property of the reaction pathway, not reactant concentration.

Answer:

A. Molecular collisions become more frequent.