2 CO (g) + O2 (g) --> 2 CO2 (g)

The mechanism below has been proposed for this reaction;

(slow) O2 + CO --> CO2 + O
(fast) O + CO --> CO2

Based on this mechanism what is the rate law for this reaction?

To determine the rate law for the reaction based on the proposed mechanism, we need to examine the individual reaction steps and identify the rate-determining step (the slowest step).

From the given mechanism:
(slow) O2 + CO --> CO2 + O
(fast) O + CO --> CO2

The slow step of the reaction is the first step, which is the only step involving O2.
Therefore, the rate-determining step is:
O2 + CO --> CO2 + O

The rate law is determined by the reactant concentrations in the rate-determining step. The slow step tells us that the concentration of O2 affects the rate of the reaction. However, we also need to consider the stoichiometry of the reaction in order to determine the overall rate law.

In the slow step, O2 and CO are reactants, and they have a stoichiometric ratio of 1:1. Therefore, we can write the rate law as:

Rate = k[O2][CO]

Where:
- Rate is the rate of the reaction
- k is the rate constant
- [O2] and [CO] are the concentrations of O2 and CO, respectively

So, the rate law for this reaction, based on the proposed mechanism, is Rate = k[O2][CO].