When the concentration of A is doubled,the rate for the reaction: 2 A + B $\rarr$ 2 C quadruples.
When the concentration of B is doubled the rate remains the same.Which mechanism below is consistent with the experimental observations?

Question

Quizplus · Accepted Answer

According to the given information, when the concentration of A is doubled, the rate of the reaction quadruples. This indicates that the reaction is second order with respect to A. 
Option C shows a slow step involving A, which is consistent with second order kinetics. 
Also, when the concentration of B is doubled, the rate remains the same, which rules out options A, B, and D since they all involve B in the rate-determining step. 
Therefore, option C is the best choice.

When the Concentration of a Is Doubled,the Rate for the Reaction