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Exam 1A
Spring 2005

Possibly useful information:

Zero Order:

[A] = –kt + [A]o

First Order:

Second Order:

Arrhenius Equation:


Kp=Kc(RT)n

R = 0.0821 L•atm/mol•K

R = 8.314 J/mol•K


1. Nomenclature:

a. Give the name for CrO42–

b. Give the molecular formula for the hydrogen phosphate ion.

2. Briefly (15 words or less) distinguish between an activated complex and an intermediate.

3. For the reaction shown below:

CO(g) + NO(g)CO2(g) + N2(g)

a. What is the ratio of the rate of loss of carbon monoxide compared to the rate of gain of nitrogen?

b. Is this an elementary reaction? Why or why not?

4. Consider the following reaction:

H2O2(aq)H2O(l) + O2(g)

which has a rate law of Rate = –k, where k = 1.0×10–3 M s–1. If [H2O2]initial = 1.0 M and [O2]initial = 0.0 M, answer the following questions:

a. What is the order of reaction with respect to hydrogen peroxide?

b. What is the concentration of hydrogen peroxide at t = 10 s?

c. What is the concentration of oxygen at t = 10 s?

5. The data listed below was collected for the following reaction:

2 HgCl2(aq) + C2O42–(aq) 2 Cl(aq) + 2 CO2(g) + Hg2Cl2(s)

Experiment

[HgCl2] (M)

[C2O42–] (M)

Initial Rate
(M min–1)

1

0.10

0.20

4.0×10–5

2

0.10

0.40

1.6×10–4

3

0.050

0.40

8.0×10–5

4

0.050

0.20

2.0×10–5

a. What is the rate law for the reaction?

b. What is the value of the rate constant for the reaction?

6. The following mechanism was proposed for a reaction:

OCl(aq) + H2O(l) HOCl(aq) + OH(aq)

I(aq) + HOCl(aq) HOI(aq) + Cl(aq)

HOI(aq) + OH(aq) H2O(l) + OI(aq)

a. Write the net reaction.

b. What is the molecularity of each reaction in the mechanism?

c.Which step is not rate determining? Why?

7. Write the mass action expression for Kc for the following reactions.

a. CO(g) + H2O(g) CO2(g) + H2(g)

b. O2(g) + NH3(g) NO(g) + H2O(g)

c. NH4HS(s) H2S(g) + NH3(g)

8. For the reaction:

N2(g) + O2(g) 2 NO(g)

Kc = 4×10–4.

Find Kc for the reaction:

NO(g) ½ N2(g) + ½ O2(g)