Name ________Beth”Key”____________________
Chemistry 2: Reaction – Chemical Kinetics Reaction Mechanisms
1. Complete the table for each elementary reaction shown.
Elementary Reaction
Molecularity
Rate Law
2NO N2O2
Bimolecular
Rate=k[NO]2
SO3 SO2 + O
Unimolecular
Rate=k[SO3]
O + O3 2O2
Bimolecular
Rate=k[O][O3]
2. The decomposition of hydrogen peroxide is catalyzed as shown below. The catalyzed
reaction is thought to proceed by a two-step mechanism:
H2O2 + I- H2O + IO- (slow)
IO- + H2O2 H2O + O2 + I- (fast)
a. Predict the rate law for the overall process
Rate=k[H2O2][I-] according to slow elementary step. However, I- is not
consumed in the reaction and therefore changing its concentration does not
impact rate. Its behavior as a catalyst will impact the value for k. This is
often designated with k’ so we can write the rate law as:
Rate=k’[H2O2]
b. Write the chemical equation for the overall process.
2H2O2 2H2O + O2
c. Identify the intermediate, if any, in the mechanism.
IO-
d. Identify the catalyst in this reaction.
I-
3. The balanced equation for the reaction of the gases nitrogen dioxide and fluorine is:
2NO2 + F2 2NO2F
The experimentally determined rate law is: Rate = K[NO2][F2]
One possible mechanism for this reaction is shown below.
NO2 + F2 NO2F + F (slow)
F + NO2 NO2F (fast)
a. What is the rate law for this mechanism?
Rate = k[NO2][F2]
b. What is the overall reaction for this mechanism?
2NO2 + F2 2NO2F
c. Is this an acceptable mechanism?
Yes
I-
