Chem 167 SI:
Friday’s material
Supplemental Instruction
Iowa State University / Leader: / Max
Course: / Chem 167
Instructor: / Burnett
Date: / Dec 8

1.  The activation energy for the reaction in which CO2 decomposes to CO and a free radical oxygen atom, O, has an activation energy of 460 kJ mol-1. The frequency factor is 2*1011s-1. What is the rate constant for this reaction at 298 K?

2.  The following mechanism is proposed for a reaction:

NO+Br2→NOBr2 slow

NOBr2+NO→2NOBr (fast)

a.  Write the overall equation for the reaction

b.  What is the rate-determining step

c.  What is the intermediate in the reaction

d.  What is the molecularity of each step

e.  Write the rate expression for each step

3.  According to an article published in 1966 in the journal of chemical education, xenon reacts photochemically with fluorine at room temperature (298 K) to produce XeF2. A portion of a table showing ratios of gases in the reaction vessel for four experiments is reproduced below. (Assume that atmospheric pressure is 1 atm). The reaction is as shown. Xeg+ F2g→XeF2(s)

Experiment / 1 / 2 / 3 / 4
Volume of Xe, in mL at 1 atm / 300 / 350 / 400 / 450
Volume of F2, in mL, at 1 atm / 271 / 260 / 262 / 183
  1. Draw the Lewis structure of XeF2, and predict the molecule’s shape.
  1. Calculate the partial pressure of each gas (mm Hg) in experiment 3
  1. Calculate the theoretical yield (mol) of XeF2 in Experiment 3 if the amounts shown are combined such that the total pressure remains 1 atm.

4.  The table below presents rate constants measured at three temperatures for the following reaction, which is involved in the production of nitrogen oxides in internal combustion engines. (assume the temperatures all have two significant figures.) Og+ N2g→NOg+ N(g)

K(L mol-1 s-1) / Temperature (K)
4.4*102 / 2000
2.5*105 / 3000
5.9*106 / 4000