1. For a reaction mechanism to be plausible, what 2 criteria must be met?
2. The reaction between CO and NO2 to produce NO and CO2 is thought to occur in 2 steps.
NO2 + NO2 ====> NO + NO3
NO3 + CO =====> NO2 + CO2
The experimental rate law is, R=k[NO2]2
Write the equation for the overall reaction.
Identify the reaction intermediates.
Identify the rate determining step.
1. In order for a reaction mechanism to be plausible, it must meet two criteria:
a) The sum of the elementary steps in the mechanism must give the overall balanced equation for the reaction.
b) The proposed mechanism must be consistent with the experimentally observed rate law for the reaction.
2. The overall reaction can be obtained by summing up the two steps of the reaction mechanism:
2NO2 + CO → 2NO + NO3 (first step)
NO3 + CO → NO2 + CO2 (second step)
By summing these two steps, we cancel out the NO3 intermediate:
2NO2 + 2CO → 2NO + NO2 + CO2
So, the overall reaction is: 2NO2 + 2CO → 2NO + NO2 + CO2
3. Reaction intermediates are the species that are formed in one step of the reaction mechanism and then consumed in a subsequent step. In this case, the reaction intermediates are NO and NO3. These species are formed in the first step and consumed in the second step.
4. The rate determining step is the slowest step in the reaction mechanism and determines the overall rate of the reaction. In this case, the first step (2NO2 + CO → 2NO + NO3) is the rate determining step as it involves two molecules of NO2, and the rate law for the reaction is R = k[NO2]2.