Chapter 16 1 Which one of the following statements regarding Kw is false

Chemistry: The Central Science, 12e (Brown et al.)

Chapter 16 Acid–Base Equilibria

16.1 Multiple–Choice Questions

1) According to the Arrhenius concept, an acid is a substance that __________.

A) is capable of donating one or more H+

B) causes an increase in the concentration of H+ in aqueous solutions

C) can accept a pair of electrons to form a coordinate covalent bond

D) reacts with the solvent to form the cation formed by autoionization of that solvent

E) tastes bitter

2) A BrØnsted-Lowry base is defined as a substance that __________.

A) increases [H+] when placed in H2O

B) decreases [H+] when placed in H2O

C) increases [OH–] when placed in H2O

D) acts as a proton acceptor

E) acts as a proton donor

3) A BrØnsted-Lowry acid is defined as a substance that __________.

A) increases Ka when placed in H2O

B) decreases [H+] when placed in H2O

C) increases [OH–] when placed in H2O

D) acts as a proton acceptor

E) acts as a proton donor

4) Which one of the following is a BrØnsted -Lowry acid?

A) (CH3)3NH+

B) CH3COOH

C) HF

D) HNO2

E) all of the above

5) A substance that is capable of acting as both an acid and as a base is __________.

A) autosomal

B) conjugated

C) amphoteric

D) saturated

E) miscible

6) Which one of the following is a BrØnsted -Lowry base?

A) (CH3)3N

B) CH3COOH

C) HF

D) HNO2

E) none of the above

7) The molar concentration of hydronium ion in pure water at 25°C is __________.

A) 0.00

B) 1.0 × 10-7

C) 1.0 × 10-14

D) 1.00

E) 7.00

8) The molar concentration of hydroxide ion in pure water at 25°C is __________.

A) 1.00

B) 0.00

C) 1.0 ×10-14

D) 1.0 × 10-7

E) 7.00

9) The magnitude of Kw indicates that __________.

A) water autoionizes very slowly

B) water autoionizes very quickly

C) water autoionizes only to a very small extent

D) the autoionization of water is exothermic

10) In basic solution, __________.

A) [H3O+] = [OH–]

B) [H3O+] > [OH–]

C) [H3O+] < [OH–]

D) [H3O+] = 0 M

E) [OH–] > 7.00

11) Which solution below has the highest concentration of hydroxide ions?

A) pH = 3.21

B) pH = 12.6

C) pH = 7.93

D) pH = 9.82

E) pH = 7.00

12) Which solution below has the highest concentration of hydronium ions?

A) pH = 3.21

B) pH = 12.6

C) pH = 7.93

D) pH = 9.82

E) pH = 7.00

13) Which one of the following statements regarding Kw is false?

A) pKw is 14.00 at 25°C

B) The value of Kw is always 1.0 × 10-14.

C) Kw changes with temperature.

D) The value of Kw shows that water is a weak acid.

E) Kw is known as the ion product of water.

14) The hydride ion, H–, is a stronger base than the hydroxide ion, OH–. The product(s) of the reaction

of hydride ion with water is/ are __________.

A) H3O+ (aq)

B) OH– (aq) + H2 (g)

C) OH– (aq) + 2H+ (aq)

D) no reaction occurs

E) H2O2 (aq)

15) An aqueous solution contains 0.10 M NaOH. The solution is __________.

A) very dilute

B) highly colored

C) basic

D) neutral

E) acidic

16) Nitric acid is a strong acid. This means that __________.

A) aqueous solutions of HNO3 contain equal concentrations of H+(aq) and OH–(aq)

B) HNO3 does not dissociate at all when it is dissolved in water

C) HNO3 dissociates completely to H+(aq) and NO3–(aq) when it dissolves in water

D) HNO3 produces a gaseous product when it is neutralized

E) HNO3 cannot be neutralized by a weak base

17) Of the following acids, __________ is a strong acid.

A) HNO2

B) H2CO3

C) HBrO3

D) HClO

E) HF

18) Of the following acids, __________ is not a strong acid.

A) HNO2

B) H2SO4

C) HNO3

D) HClO4

E) HCl

19) Of the following, __________ is a weak acid.

A) HF

B) HCl

C) HBr

D) HNO3

E) HClO4

20) Which one of the following is the weakest acid?

A) HF (Ka = 6.8 × 10-4)

B) HClO (Ka = 3.0 × 10-8)

C) HNO2 (Ka = 4.5 × 10-4)

D) HCN (Ka = 4.9 × 10-10)

E) Acetic acid (Ka = 1.8 × 10-5)

21) Of the acids in the table below, __________ is the strongest acid.

A) HOAc

B) HCHO2

C) HClO

D) HF

E) HOAc and HCHO2

22) The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25.0°C. What is the % ionization of

hypochlorous acid in a 0.015 M aqueous solution of HClO at 25.0°C?

A) 4.5 × 10-8

B) 14

C) 2.1 × 10-5

D) 0.14

E) 1.4 × 10-3

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

ionization?

A) 0.01 M HC2H3O2 (Ka = 1.8 × 10-5)

B) 0.01 M HNO2 (Ka = 4.5 × 10-4)

C) 0.01 M HF (Ka = 6.8 × 10-4)

D) 0.01 M HClO (Ka = 3.0 × 10-8)

E) These will all exhibit the same percentage ionization.

24) Classify the following compounds as weak acids (W) or strong acids (S):

benzoic acid nitric acid acetic acid

A) W W W

B) S S S

C) S W W

D) W S S

E) W S W

25) Classify the following compounds as weak acids (W) or strong acids (S):

hydrocyanic acid hydrofluoric acid phenol

A) W W W

B) S S S

C) S W W

D) W S S

E) W S W

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

ionization?

A) 0.01 M HC2H3O2 (Ka = 1.8 × 10-5)

B) 0.01 M HNO2 (Ka = 4.5 × 10-4)

C) 0.01 M HF (Ka = 6.8 × 10-4)

D) 0.01 M HClO (Ka = 3.0 × 10-8)

E) These will all exhibit the same percentage ionization.

27) Classify the following compounds as weak acids (W) or strong acids (S):

nitrous acid hydrochloric acid hydrofluoric acid

A) W W W

B) S S S

C) S W W

D) W S S

E) W S W

28) Classify the following compounds as weak acids (W) or strong acids (S):

hypochlorous acid perchloric acid chloric acid

A) W S S

B) S S S

C) S W W

D) W W W

E) W S W

29) Ammonia is a __________.

A) weak acid

B) strong base

C) weak base

D) strong acid

E) salt

30) HA is a weak acid. Which equilibrium corresponds to the equilibrium constant Kb for A–?

A) HA (aq) + H2O (l) H2A+ (aq) + OH– (aq)

B) A– (aq) + H3O+ (aq) HA (aq) + H2O (l)

C) HA (aq) + OH– (aq) H2O (l) + H+ (aq)

D) A– (aq) + H2O (l) HA (aq) + OH– (aq)

E) A– (aq) + OH– (aq) HOA2- (aq)

31) A- is a weak base. Which equilibrium corresponds to the equilibrium constant Ka for HA?

A) HA (aq) + H2O (l) H2A+ (aq) + OH– (aq)

B) A– (aq) + H3O+ (aq) HA (aq) + H2O (l)

C) HA (aq) + H2O (l) H3O+ (aq) + A– (aq)

D) A– (aq) + H2O (l) HA (aq) + OH– (aq)

E) A– (aq) + OH– (aq) HOA2- (aq)

32) Classify the following compounds as weak bases (W) or strong bases (S):

ammonia fluoride ion sodium hydroxide

A) W W S

B) S S S

C) S W W

D) W S S

E) W S W

33) Classify the following compounds as weak bases (W) or strong bases (S):

methylamine carbonate ion potassium hydroxide

A) W W S

B) S S S

C) S W W

D) W S S

E) W S W

34) Using the data in the table, which of the conjugate bases below is the strongest base?

A) OAc–

B) C7H5O2–

C) NO2–

D) F–

E) OAc– and C7H5O2–

35) Using the data in the table, which of the conjugate bases below is the weakest base?

A) OAc–

B) C7H5O2–

C) NO2–

D) F–

E) OAc– and C7H5O2–

36) Using the data in the table, which of the conjugate bases below is the strongest base?

A) OAc–

B) CHO2–

C) ClO–

D) F–

E) OAc– and CHO2–

37) Using the data in the table, which of the conjugate bases below is the weakest base?

A) OAc–

B) CHO2–

C) ClO–

D) F–

E) OAc– and CHO2–

38) Using the data in the table, which of the conjugate acids below is the strongest acid?

A) HClO

B) HCO3–

C) H2S

D) NH3CH3+

E) H2S and HClO

39) Using the data in the table, which of the conjugate acids below is the weakest acid?

A) HClO

B) HCO3–

C) H2S

D) NH3CH3+

E) H2S and HClO

40) Using the data in the table, which of the conjugate acids below is the strongest acid?

A) NH4+

B) C5H5NH+

C) H3NOH+

D) NH3CH3+

E) NH4+ and NH3CH3+

41) Using the data in the table, which of the conjugate acids below is the weakest acid?

A) NH4+

B) C5H5NH+

C) H3NOH+

D) NH3CH3+

E) NH4+ and NH3CH3+

42) Which of the following ions will act as a weak base in water?

A) OH–

B) Cl–

C) NO3–

D) ClO–

E) None of the above will act as a weak base in water.

43) Which of the following ions will act as a weak base in water?

A) HS–

B) F–

C) NO2–

D) ClO–

E) All of the above will act as a weak base in water.

44) Which of the following aqueous solutions has the highest [OH–]?

A) a solution with a pH of 3.0

B) a 1 × 10-4 M solution of HNO3

C) a solution with a pOH of 12.0

D) pure water

E) a 1 × 10-3 M solution of NH4Cl

45) Which of the following aqueous solutions has the lowest [OH–]?

A) a solution with a pH of 3.0

B) a 1 × 10-4 M solution of HNO3

C) a solution with a pOH of 12.0

D) pure water

E) a 1 × 10-3 M solution of NH4Cl

46) A 0.0035 M aqueous solution of a particular compound has pH = 2.46. The compound is

__________.

A) a weak base

B) a weak acid

C) a strong acid

D) a strong base

E) a salt

47) Of the following substances, an aqueous solution of __________ will form basic solutions.

NaHS Cu(NO3)2 KHCO3 NaF

A) NaHS, Cu(NO3)2

B) KHCO3, NaHS

C) NaF only

D) NaF, KHCO3

E) NaHS, KHCO3 and NaF

48) Of the following substances, an aqueous solution of __________ will form basic solutions.

NH4Cl Cu(NO3)2 K2CO3 NaF

A) NH4Cl, Cu(NO3)2

B) K2CO3, NH4Cl

C) NaF only

D) NaF, K2CO3

E) NH4Cl only

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

NaOCl KCl NH4Cl Ca(OAc)2

A) NaOCl

B) KCl

C) NH4Cl

D) Ca(OAc)2

E) KCl and NH4Cl

50) Of the compounds below, a 0.1 M aqueous solution of __________ will have the highest pH.

A) KCN, Ka of HCN = 4.0 × 10-10

B) NH4NO3, Kb of NH3 = 1.8 × 10-5

C) NaOAc, Ka of HOAc = 1.8 × 10-5

D) NaClO, Ka of HClO = 3.2 × 10-8

E) NaHS, Kb of HS– = 1.8 × 10-7

51) A 0.1 M solution of __________ has a pH of 7.0.

A) Na2S

B) KF

C) NaNO3

D) NH4Cl

E) NaF

52) An aqueous solution of __________ will produce a basic solution.

A) NH4ClO4

B) KBr

C) NaCl

D) NaHSO4

E) Na2SO3

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

A) HIO

B) HIO4

C) HIO2

D) HIO3

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

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

A) HIO

B) HIO4

C) HIO2

D) HIO3

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

55) Which of the following acids will be the strongest?

A) H2SO4

B) HSO4–

C) H2SO3

D) H2SeO4

E) HSO3–

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

A) HClO

B) HClO3

C) HClO2

D) HClO4

E) HIO

57) In the gas phase reaction below, NH3 is acting as a(n) __________ base but not as a(n) __________

base.

H+

. . |

N + H+ → N

| |

H H H H H H

A) Arrhenius, BrØnsted-Lowry

B) BrØnsted-Lowry, Lewis

C) Lewis, Arrhenius

D) Lewis, BrØnsted-Lowry

E) Arrhenius, Lewis

16.2 Bimodal Questions

1) What is the conjugate acid of NH3?

A) NH3

B) NH2+

C) NH3+

D) NH4+

E) NH4OH

2) What is the conjugate acid of CO3-2?

A) CO2-2

B) HCO2-2

C) H2CO3

D) HCO3–

E) none of the above