CHEM 113 TEST #3 SPRING 1998 DR. BRYAN

Use the following reaction for Questions 1 - 3:

3Fe (s) + 4H2O (g) Fe3O4 (s) + 4H2 (g)

1. The equilibrium constant expression for Kp is

" Answers for this question wouldn't transfer"

2. Solving for KC in terms of KP , you would get the expression

A. Kc = Kp

B. Kc = Kp (RT)

C. Kc = Kp / (RT)

D. Kc = Kp (RT)2

E. Kc = Kp (RT)0.5

3. If the reaction above were in equilibrium and pressure were decreased then:

A. the reaction will shift to the left to come to equilibrium.

B. the reaction will shift to the right to come to equilibrium.

C. no change will occur.

4. For the following equilibrium:

H2 (g) + Br2 (g) 2 HBr (g) K = 1.8 x 102

If the a initial mixture of the gases above had the concentrations:

[H2] = 0.10 M [Br2] = 0.10 M [HBr] = 0.20 M

then

A. the reaction will shift to the left to come to equilibrium.

B. the reaction will shift to the right to come to equilibrium.

C. no change will occur.

5. Which of the following acids will have the least ionization in water?

A. HCl B. HNO2 C. HC2H3O2 D. H2S E. all are about the same

6. Which of the following is the strongest base in water?

A. Cl- B. ClO4- C. F- D. NO3- E. H2O

7. In the reaction, NH3(aq) + H2O (l) H3O+ (aq) + NH2- (aq),

NH3 is acting as:

A. a Bronsted-Lowry base

B. a Bronsted-Lowry acid

C. a Lewis acid

D. a Lewis base

E. an Arrhenius base

8. As [H3O+ ] decreases in a solution:

A. pH increases

B. pOH increases

C. the solution becomes more acidic

D. Both A and C

E. None of these

9. Which of the following is (are) conjugate acid/base pairs?

A. H3O+, OH-

B. NH4+ , NH2-

C. HCl, H3O+

D. A and B

E. none of these

10. Which is true concerning the following acids:

HClO2 HIO2 HBrO2

A. HBrO2 is stronger than HIO2 .

B. HClO2 is the weakest of the three acids.

C. HIO2 is the strongest of the three acids.

D. A and B are true.

E. B and C are true.

11. What is the value of Kb for the H2PO4- ion?

A. 7.5 x 10-3

B. 6.2 x 10-8

C. 1.0 x 10-12

D. 1.6 x 10-7

E. 1.3 x 10-12

12. Which of following solutions would have a pH of nearly 7.0?

A. 0.1 M HCl

B. 0.1 M NaC2H3O2

C. 0.1 M NH4Cl

D. 0.1 M NaClO4

E. 0.1 M Na F

13. A species which can both donate and accept H+ ions is called _______________________.

A. automorphic

B. amphibious

C. autoprotolytic

D. amphiprotic

E. ambidextrous

14. In the reaction, HC2H3O2 (aq) + H2O (l) H3O+ (aq) + C2H3O2- (aq),

the two substances acting as bases are:

A. HC2H3O2 and H3O+

B. C2H3O2- and H2O

C. H3O+ and C2H3O2-

D. HC2H3O2 and H2O

E. all substances are acting as bases

15. pOH = 3.1 is equivalent to

A. pH = 11.9

B. [H3O+] = 1.3 x 10-11

C. [OH-] = 7.9 x 10-5

D. acidic solution

E. neutral solution

16. Which of the following statements is true concerning a weak diprotic acid solution,

0.1 M H2Z (aq) Ka1 = 1.8 x 10-5 , Ka2 = 3.5 x 10-9

A. the pH of this solution is about 1.0

B. the pH of this solution is about the same as 0.10 M HCl (aq).

C. the pH of this solution is about the same as 0.10 M HC2H3O2 (aq).

D. the pH of this solution is about the same as 0.10 M H2S (aq).

E. the pH of this solution is about the same as 0.10 M H2SO4 (aq).

17. Determine K for the following equilibrium (using your acid/base chart):

HF(aq) + NH3 (aq) NH4+ (aq) + F- (aq) , K=?

A. 7.2 x 10-4

B. 1.3 x 106

C. 1.8 x 109

D. 1.4 x 103

E. 7.8 x 10-7

18. What are the primary species in a solution labeled 0.10 M NaHCO3 ?

A. Na+ , OH- , H2O

B. Na+ , H2O

C. Na+ , HCO3- , H2O

D. Na+ , CO32- , H2O

E. Na+ , H3O+ , H2O

19. Which of the following pairs of solutions (when mixed) is least likely to have a good net reaction?

A. HCO3- , OH-

B. H3O+ , CO32-

C. HS- , NH3

D. HCN , OH-

E. all of these will have good net reactions

20. What is the net ionic equation when:

a solution of HCl (aq) is mixed with a solution of NaF (aq) ?

A. H3O+ (aq) + OH- (aq) H2O (l) + H2O (l)

B. HCl (aq) + OH- (aq) H2O (l) + Cl- (aq)

C. H3O+ (aq) + F- (aq) HF (aq) + H2O (l)

D. HCl (aq) + F- (aq) HF (aq) + Cl- (aq)

E. HCl (aq) + H2O (l) H3O+ (aq) + Cl- (aq)

21. Which of the following shows the base ionization reaction for HSO4- ?

A. HSO4- (aq) + H2O (l) H3O+ (aq) + SO42- (aq)

B. HSO4- (aq) + H2O (l) H2SO4 (aq) + OH- (aq)

C. HSO4- (aq) + OH- (aq) H2O (aq) + SO42- (aq)

D. HSO4- (aq) + H3O+ (aq) H2SO4 (aq) + H2O (l)

E. none of these

22. Calculate the pH of a solution of 0.375 benzoic acid. (Ka for benzoic acid = 6.3 x 10-5 )

A. 2.3

B. 4.9

C. 5.1

D. 0.43

E. 11.7


23. Calculate the pH of a solution of 0.240 M KCN.

A. 11.4

B. 2.6

C. 8.7

D. 13.4

E. 9.4


24. What is the pH of a solution prepared by dissolving 0.140 g of potassium hydroxide in enough water to make 250.0 mL of solution?

A. 2

B. 6

C. 8

D. 10

E. 12


25. Initially a mixture contains [A]0 = 0.392 M and [B]0 = 0.452 M ( and no C and D are

present). At equilibrium, [C]0 = 0.0128 M. Calculate the concentration of A at equilibrium (using the equation below).

3 A(g) + 2 B(g) C (g) + D(g) K is not known

A. 0.0128 M

B. 0.379 M

C. 0.354 M

D. 0.366 M

E. 0.430 M

26. Calculate the % ionization of 0.50 M HQ(aq), Ka for HQ is 1.3 x 10-6.

A. 0.08%

B. 0.2%

C. 1%

D. 2%

E. 100%

27. Using the equation below, calculate the equilibrium concentration of N2 in a container

which initially contains only NH3 (g) at a concentration of 0.50 M.

2NH3 (g) N2 (g) + 3 H2 (g) K = 2.1 x 10-7

A. 1.9 x 10-9 M

B. 1.2 x 10-2 M

C. 7.9 x 10-3 M

D. 6.6 x 10-3 M

E. 1.4 x 10-7 M