Supplemental General Chemistry

Exam 2 (cumulative chapter 13, 14, 6 and 18): 150 points
Due Tuesday, May 6, by 4pm, online under the Assignments tab in Oncourse.
To receive full credit, show all your work on problems that have worked answers
(calculations). Answers alone will not be given full credit.

1. One reaction thought to occur in air pollution is the following reaction:
2 No (g) + 02 (g) \> 2 No2 (g)

Use the data in the table below to answer the following questions.

2 0.0010 0.0010 7.0 x 105
2 0.0010 0.0020 1.4 x 10’5
I 0.0010 0.0030 2.1 x 10’5
n 0.0020 0.0030 8.4 x 10’5
I 0.0030 0.0030 1.9 x 104

a.) (4 points) Write the rate law for the reaction.

b.) (4 points) Calculate the rate constant and express it with the correct units.

c.) (4 points) Calculate the rate of formation of No2 when [No] = [02] = 00050 M

d.) (4 points) If 02 disappears at a rate of 1.0 x 104 M/s, what is the rate at which NO disappears? What i
the rate at which No2 is forming?

e.) (4 points) Draw a graph that indicates the change in concentration of each species (reactant and
product) as a function of time. Label each ofthe three of your curves and make sure that they have a
quantitative relevance.

2. The following reaction has an equilibrium constant, Kc, of 5.8 x 103 at 25 °C. Suppose 15.6 g of N204 is
placed into a sealed 5.0-L flask and allowed to come to equilibrium.

a.) (5 points) Calculate the concentration of No2 present at equilibrium.

b.) (5 points) Calculate the percentage of original N204 has dissociated when it reaches equilibrium.