# PRACTICE PROBLEMS CHM 12

**Topics:**Acetic acid, Acid dissociation constant, Buffer solution

**Pages:**8 (1202 words)

**Published:**April 24, 2015

a) 1.8

b) -1.8

c) 0.015 M

d) 3.3

e) -3.3

2. What is the pOH of the solution in Problem #1?

a) 10.7

b) 17.3

c) 12.2

d) 15.8

e) 7.0

3. The Ka of acetic acid is 1.8 x 10-5. What is its pKa?

a) 1.8 x 10-5

b) 5.18

c) 4.74

d) -4.74

4. What is the pH of a 0.100 M solution of acetic acid?

a) 1.34 x 10-3

b) 2.87

c) 1.00

d) 4.74

e) 3.74

5. What is the acetate ion (Ac- or CH3COO-) concentration of the solution in Problem #4?

a) exactly zero

b) 3.74 M

c) 0.100 M

d) 1.34 x 10-3 M

e) 1.8 x 10-6 M

6. What is the percent ionization of the acetic acid in Problem #4?

a) 1.34%

b) 0.134%

c) 0.0014%

d) 1.8 x 10-5 %

e) 1.8 x 10-3 %

7. What is the pH of 6.0 M aqueous solution of NH3 (ammonia). It's Kb = 1.8 x 10-5.

a) 0.0104

b) 1.98

c) 0.778

d) 12.0

e) 13.2

8. What is the NH4+ concentration of the solution in Problem #7?

a) 6.0 M

b) 0.0104 M

c) 1.8 x 10-4 M

d) 1.8 x 10-5 M

9. HNO2 has a pKa = 3.35 and HOCl has a pKa = 7.45. Which is the stronger acid?

a) HNO2

b) HOCl

10. Based on the information given in Problem #9, what is the Ka of HNO2?

a) 5.25 x 10-1

b) 2.24 x 103

c) 3.5 x 10-3

d) 4.46 x 10-4

e) 1.8 x 10-5

11. What is the H2O species concentration in any dilute aqueous solution?

a) zero

b) infinite

c) 55.5 M

d) 1.0 M

e) 1.0 x 10-7 M

12. Which is the most likely pH of Windex glass cleaner?

a) 2

b) 4

c) 7

d) 12

e) 14

13. A particular vinegar solution has a H3O+ concentration of 0.015 M. What is the pH of the solution?

a) 1.8

b) -1.8

c) 0.015 M

d) 3.3

e) -3.3

14. What is the pH of a 0.10 M solution of HF in water? The Ka = 7.2 x 10- 4.

a) -2.07

b) 8.5 x 10-3

c) 0.10

d) 3.14

e) 2.1

15. What is the percent ionization of the acid in Problem #14?

a) 100%

b) 8.5%

c) 0.11%

d) 0.0011%

e) 0.08%

16. What is the pH of a 0.20 M aqueous solution of the base methylamine, CH3NH2? Kb = 5.0 x 10-4.

a) 2.0

b) 12.0

c) 16.0

d) 10.0

e) 0.01

17. A buffer solution is prepared by the addition of 20.0 grams of HF and 21.0 grams of NaF to enough water to make 1.000 L of solution. The Ka of HF is 7.2 x 10-4. What is the pH of this solution?

a) 3.44

b) 3.14

c) 2.84

d) 7.0

e)2.4

18. Which of the following pairs of compounds dissolved together in aqueous solution would NOT make a good buffer solution?

a) HNO3/NaNO3

b) H3PO4/NaH2PO4

c) H2CO3/KHCO3

d) HCN/KCN

19. A buffer solution is 0.10 M HAc (acetic acid) and 0.10 M NaAc (sodium acetate) and we have 1.000 Liter of it. What is the pH after 0.010 moles of HCl are added to this solution?

a) -2.0

b) 4.74

c) 4.82

d) 2.0

e) 4.65

20. We desire to make a buffer solution with a pH of 9.2. Which combination of compounds would be the best to use? Refer to the table of bases given.

a) HAc/NaAc

b) NH3/NH4Cl

c) HCl/NaCl

d) pyridine/pyridine chloride

21. A solution is prepared which is 1.0 M acetic acid. What would happen to the pH of this solution if potassium acetate were added to the solution?

a) pH would go up

b) pH would go down

c) would not affect the pH

22. A buffer solution has a pH = 5.5. What is the [H3O+] concentration?

a) 5.5 M

b) 3.16 x 10-6 M

c) 3.2 x 105 M

d) 0.74 M

e) 3.2 x 10-3 M

23. Calculate the H+ (aq) concentration of 0.50 M solution of HNO2.

a) 0.50 M

b) 0.015 M

c) 4.5 x 10-4 M

d) 0.30 M

e) 1.82 M

24. Calculate the percent ionization of the acid HF(aq) in 1.0 M aqueous HF solution.

a) 7.2 x 10-4 %

b) 0.072 %

c) 2.68 %

d) 100 %

25. Calculate the OH- concentration in 0.50 M aqueous NH3 solution.

a) 0.0030 M

b) 0.50 M

c) zero

d) 4.2 x 10-3 M

26. Calculate the pH of a 2.0 M aqueous solution of the base methylamine, which has a Kb = 5.0 x 10-4.

a) 2.0

b) 14.3

c) 13.3

d) 12.5

e) 3.3

27. An indicator symbolically given as HIn can be in two different forms: as HIn (red) or as In- (yellow). The pKa of the indicator is 4.0....

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