Question

Consider the reaction below:

2NO2(g) + F2(g) ⟶ 2NO2F(g)

a. Based on the information provided in the table below (all measurements are at 25 ºC), determine the

experimental rate law and calculate the rate constant at this temperature. You can assume ideal gas

behavior for both NO2 and F2.

Initial Pressures (atm) Experiment p(NO2); p(F2) (mol L-1 s-1)

1) .038 ; .060

2) .076 ; .060

3) .076 ; .030

Initial Rate

1 0.038 0.060 1.4  10– 5

2 0.076 0.060 2.8  10– 5

3 0.076 0.030 1.4  10– 5

b. Contrasting NO2 and F2, which one of these two real gases would be closer to ideal gas assumed in part a?

Draw the Lewis structures of both to support your argument.

c. Based on the rate law determined in part a, propose a reaction mechanism comprising of two bimolecular

elementary steps. Hint: F is an intermediate in the overall reaction.

d. Which elementary process in part c is rate-determining?

e. You conduct experiment 1 from the table in part a. If your initial p(NO2) is 0.038 atm and p(F2) is kept at

constant flow of 0.060 atm, how long would it take for the pressure of NO2 to drop to 0.001 atm?

f. The collision frequency and steric factor for the rate-determining step in the overall process at 25 ºC are

5.9x1010 and 0.16, respectively. Calculate the activation energy (in kJ/mol) for the rate determining step.

g. If the enthalpy of reaction (i.e. standard enthalpy change for the overall process) is -100 kJ/mol, sketch the

energy profile of the two-step reaction given that i) the activation energy for the fast step in part c is 5

kJ/mol and ii) equilibrium partial pressures of all species involved in the fast step are 1.0 atm