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Exam 1B
Spring 2004

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 H2PO4

b. Give the molecular formula for the nitrite ion.

2. The following reaction has a rate constant k = 1.0×10–10 s–1 at 25 oC.

[Co(NH3)6]2+(aq) + H2O(l) [Co(NH3)5(H2O)]2+(aq) + NH3(aq)

a. Write the rate law for the reaction.

b. What is the initial rate of reaction if the initial concentration of [Co(NH3)6]2+ is 1.0 M?

c. If the initial concentration of [Co(NH3)6]2+ is 1.0 mM, what is the half-life of the reaction?

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

3. A student measured the rate constants at several temperatures for the following reaction and made the plots shown.

[Ir(Cl)(CO)(P(C6H5)3)2](benzene) + H2(g) [Ir(H2)(Cl)(CO)(P(C6H5)3)2](benzene)

a. What is the order of reaction?

b. What is the rate constant for the reaction at 50 oC?

c. What is the activation energy in units of kJ/mol? The value of R used for the indicated calculations is 8.314 J/mol•K

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

[Cr(CO)4(P(OC6H5)3)(As(C6H5)3)] products

Time (min)

Concentration (M)

2

0.374

7

0.312

14

0.259

22

0.203

32

0.155

43

0.108

54

0.078

67

0.050

a. What is the order of reaction?

b. Estimate the half-life in units of minutes.

5. The following mechanism was proposed for a reaction:

[IrCl6]2–(aq) + [W(CN)8]4–(aq) [IrCl62–---W(CN)84– ](aq)

[IrCl62–---W(CN)84– ](aq) [IrCl63–---W(CN)83– ](aq)

[IrCl63–---W(CN)83– ](aq) [IrCl6]3–(aq) + [W(CN)8]3–(aq)

a. Write the net reaction.

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

c.Which step is rate determining? Why?

d. Write the rate law for the net reaction.

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

a. HI(g) H2(g) + I2(g)

b. CO(g) + H2(g) CH3OH(g)

c. HBr(g) + NH3(g) NH4Br(s)

7. Consider the following set of reactions:

A(g) B(g)      Kp = 10

B(g) + C(g) D(g)      Kp = 100

D(g) E(g)      Kp = 0.1

Find the equilibrium constant for the reaction:

A(g) + E(g) 2 B(g) + C(g)