Chapter 16 3 What is the pOH of an aqueous solution at 25.0 °C in which

12) What is the pOH of an aqueous solution at 25.0 °C in which [OH–] is 0.0010 M?

A) 11.00

B) -3.00

C) 3.00

D) -11.00

E) 6.91

13) What is the concentration (in M) of hydronium ions in a solution at 25.0 °C with pH = 4.146?

A) 4.15

B) 9.85

C) 1.40 × 10-10

D) 7.15 × 10-5

E) none of the above

14) What is the concentration (in M) of hydroxide ions in a solution at 25.0 °C with pH = 4.282?

A) 4.28

B) 9.72

C) 1.92 × 10-10

D) 5.22 × 10-5

E) none of the above

15) An aqueous solution contains 0.10 M HNO3. The solution is ________.

A) acidic

B) basic

C) neutral

D) very dilute

E) highly colored

16) Which solution will be the most basic?

A) 0.10 M Ba(OH)2

B) 0.10 M KOH

C) 0.10 M H2O

D) 0.10 M CH3OH

E) All solutions have equal basicity.

17) A 1.0 × 10-2 M aqueous solution of Ca(OH)2 at 25.0 °C has a pH of ________.

A) 12.30

B) 1.70

C) 2.0 × 10–2

D) 5.0 × 10–13

E) 12.00

18) What is the pH of a 0.020 M aqueous solution of barium hydroxide?

A) 12.60

B) 12.30

C) 1.70

D) 10.41

E) 1.40

19) What is the pOH of a 0.030 M solution of barium hydroxide?

A) 12.78

B) 12.48

C) 1.52

D) 1.22

E) 10.41

20) Hydrochloric acid is a strong acid. This means that ________.

A) HCl dissociates completely to H+(aq) and Cl–(aq) when it dissolves in water

B) HCl does not dissociate at all when it is dissolved in water

C) HCl produces a gaseous product when it is neutralized

D) HCl cannot be neutralized by a weak base

E) aqueous solutions of HCl contain equal concentrations of H+(aq) and OH–(aq)

21) The acid-dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10-8. At equilibrium,

the molarity of H3O+ in a 0.066 M solution of HClO is ________.

A) 4.4 × 10-5

B) 0.066

C) 2.2 × 10–10

D) 4.35

E) 1.18

22) In which of the following aqueous solutions does the weak acid exhibit the highest percentage

ionization?

A) 0.01 M H2SO3 (Ka = 1.4 × 10-2)

B) 0.01 M HCN (Ka = 6.2 × 10–10)

C) 0.01 M H2CO3 (Ka = 4.5 × 10-7)

D) 0.01 M HC3H5O2 (Ka = 1.3 × 10-5)

E) 0.01 M HOCl (Ka = 3.5 × 10-8)

23) In which of the following aqueous solutions does the weak acid exhibit the lowest percentage

ionization?

A) 0.01 M HCN (Ka = 6.2 × 10–10)

B) 0.01 M H2CO3 (Ka = 4.5 × 10-7)

C) 0.01 M HNO2 (Ka = 4.0 × 10-4)

D) 0.01 M HCHO2 (Ka = 1.8 × 10-4)

E) 0.01 M HOCl (Ka = 3.5 × 10-8)

24) The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25.0 °C. Calculate the pH of a 0.0385 M

hypochlorous acid solution.

A) 3.05

B) 9.53

C) 4.47

D) 6.52

E) -3.05

25) The Ka of hydrofluoric acid (HF) at 25.0 °C is 6.8 × 10-4. What is the pH of a 0.45 M aqueous solution

of HF?

A) 4.05

B) 1.76

C) 3.64

D) 0.35

E) 1.41

26) The Ka of hydrazoic acid (HN3) is 1.9 × 10-5 at 25.0 °C. What is the pH of a 0.15 M aqueous solution of

HN3?

A) 0.82

B) 1.95

C) 5.23

D) 2.77

E) -3.46

27) The base-dissociation constant of ethylamine (C2H5NH2) is 6.4 × 10-4 at 25.0 °C. The [H+] in a

1.4 × 10-2 M solution of ethylamine is ________ M.

A) 3.7 × 4.9 × 10–12

B) 2.7 × 10-3

C) 3.3 × 10–12

D) 3.0 × 10-3

E) 11.43

28) Calculate the pH of a 0.500 M aqueous solution of NH3. The Kb of NH3 is 1.77 × 10-5.

A) 8.95

B) 11.47

C) 2.53

D) 11.77

E) 2.23

29) A 0.1 M aqueous solution of ________ will have a pH of 7.0 at 25.0 °C.

LiF RbBr NaClO4 NH4Cl

A) RbBr and NaClO4

B) LiF and RbBr

C) NaClO4 only

D) LiF only

E) NH4Cl only

30) An aqueous solution of ________ will produce a basic solution.

A) Na2SO3

B) RbBr

C) Mg(ClO4)2

D) NH4NO3

E) KNO3

31) An aqueous solution of ________ will produce an acidic solution.

A) NH4I

B) KBr

C) Sr(ClO4)2

D) K2CO3

E) NaNO3

32) An aqueous solution of ________ will produce a neutral solution.

A) LiNO3

B) NaNO2

C) KF

D) Rb2CO3

E) NH4NO3

38

33) The acid-dissociation constant of hydrocyanic acid (HCN) at 25.0 °C is 4.9 × 10–10. What is the pH of

an aqueous solution of 0.050 M sodium cyanide (NaCN)?

A) 11.00

B) 3.00

C) 1.0 × 10–3

D) 9.9 × 10–12

E) 2.5 × 10–11

34) Calculate the pOH of a 0.0727 M aqueous sodium cyanide solution at 25.0 °C. Kb for CN– is

4.9 × 10–10.

A) 9.33

B) 10.00

C) 5.22

D) 1.14

E) 8.78

35) Calculate the pH of a 0.0727 M aqueous sodium cyanide solution at 25.0 °C. Kb for CN– is 4.9 × 10–10.

A) 9.33

B) 10.00

C) 5.22

D) 1.14

E) 8.78

36) Determine the pH of a 0.15 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.

A) 0.82

B) 5.83

C) 8.17

D) 5.01

E) 1.17

37) Determine the pOH of a 0.10 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.

39

A) 1.00

B) 5.92

C) 8.08

D) 5.01

E) 1.58

38) Calculate the pH of 0.726 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that Kb

for aniline is 3.83 × 10-4.

A) 1.78

B) 12.22

C) 5.36

D) 8.64

E) 12.42

39) Calculate the pOH of 0.606 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that Kb

for aniline is 3.83 × 10-4.

A) 1.82

B) 12.18

C) 5.40

D) 8.60

E) 12.42

40) Kb for NH3 is 1.8 × 10-5. What is the pH of a 0.40 M aqueous solution of NH4Cl at 25.0 °C?

A) 2.57

B) 11.43

C) 9.18

D) 4.82

E) 11.23

41) Kb for NH3 is 1.8 × 10-5. What is the pOH of a 0.20 M aqueous solution of NH4Cl at 25.0 °C?

A) 2.72

B) 11.28

C) 9.02

D) 4.98

E) 11.23

42) The Ka for formic acid (HCO2H) is 1.8 × 10-4. What is the pH of a 0.20 M aqueous solution of sodium

formate (NaHCO2)?

A) 11.64

B) 5.48

C) 3.39

D) 8.52

E) 4.26

43) Of the following, which is the strongest acid?

A) HIO4

B) HIO3

C) HIO2

D) HIO

E) The acid strength of all of the above is the same.

44) Of the following, which is the weakest acid?

A) HPO3–

B) H3PO4

C) H2PO4–

D) HPO4–

E) The acid strength of all of the above is the same.

16.4 Short Answer Questions

1) A solution of acetic acid is 2.0% dissociated at 25.0°C. What was the original concentration (in M) of the

acetic acid solution? The Ka at 25.0 °C for acetic acid is 1.8 × 10-5.

2) A solution of formic acid is 3.0% dissociated at 25.0 °C. What is the original concentration (in M) of the

formic acid solution? The Ka at 25.0 °C for formic acid is 1.8 × 10-4.

3) A solution of ammonia is 2.0% ionized at 25.0 °C. What was the original concentration (in M) of the

ammonia solution? The Kb at 25.0 °C for ammonia is 1.8 × 10-5.

4) What is the pH of a sodium acetate (NaC2H3O2) solution prepared by adding 0.820 grams of sodium

acetate to 100.0 ml of water at 25.0 °C? The Ka at 25.0 °C for acetic acid is 1.8 × 10-5.

5) What is the pH of a sodium formate (NaCHO2) solution prepared by adding 0.680 grams of sodium

formate to 100.0 ml of water at 25.0 °C? The Ka at 25.0 °C for formic acid is 1.8 × 10–4.

16.5 True/False Questions

1) In the reaction

BF3 + F– → BF4–

BF3 acts as a Br∅nsted-Lowry acid.

2) An acid containing the COOH group is called a carbo-oxy acid.

3) A Lewis acid is an electron-pair acceptor, and a Lewis base is an electron-pair donor.