Question

Given the following proposed mechanism, predict the rate law for the rate-determining step.

2 NO2 + Cl2 → 2 NO2Cl (overall reaction)

MechanismNO2 + Cl2 → NO2Cl + Cl (slow)NO2 + Cl → NO2Cl (fast)A) Rate = k[NO2][Cl]B) Rate = k[NO2Cl][Cl]C) Rate = k[NO2]2[Cl2]D) Rate = k[NO2][Cl2]E) Rate = k[NO2Cl]2

Answer 1

D) Rate = K [NO2][Cl2]

Step-by-step explanation:

2 NO2 + Cl2 → 2 NO2Cl (overall reaction)

NO2 + Cl2 → NO2Cl + Cl (slow)

NO2 + Cl → NO2Cl (fast)

The rate-determining step is the slowest step in a reaction mechanism. Because it is the slowest, it determines the rate of the overall reaction.

Rate of reaction is typically given as;

Rate = K [Reactants]

In the slow step i the reaction mechanism, the reactants are; NO2 and Cl2. Since both are not intermediates, there is no need for further working out.

Rate = K [NO2][Cl2]