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

Chemistry: The Central Science, 13e (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 Br∅nsted-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 Br∅nsted-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 Br∅nsted-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) ambiprotic

D) saturated

E) miscible

6) Which one of the following is a Br∅nsted-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) 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.

11) 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)

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12) Of the following acids, ________ is a strong acid.

A) HNO2

B) H2CO3

C) HNO3

D) HClO

E) HF

13) Of the following acids, ________ is not a strong acid.

A) HNO2

B) H2SO4

C) HNO3

D) HClO4

E) HCl

14) Of the following, ________ is a weak acid.

A) HF

B) HCl

C) HBr

D) HNO3

E) HClO4

15) 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)

16) Of the acids in the table below, ________ is the strongest acid.

A) HOAc

B) HCHO2

C) HClO

D) HF

E) HOAc and HCHO2

17) The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25 °C. What is the percent ionization of

hypochlorous acid in a 0.015 M aqueous solution of HClO at 25 °C?

A) 4.5 × 10-8

B) 14

C) 2.1 × 10–5

D) 0.14

E) 1.4 × 10-3

18) 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

19) 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

20) 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

21) 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

22) Ammonia is a ________.

A) weak acid

B) strong base

C) weak base

D) strong acid

E) salt

23) 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)

24) 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)

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25) 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

26) 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

27) 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–

28) 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–

29) 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–

30) 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–

31) 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

32) 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

33) 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+

34) 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+

35) 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.

36) 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.

37) 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

38) 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

39) 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

40) 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

41) 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

42) 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

43) A 0.1 M solution of ________ has a pH of 7.0.

A) Na2S

B) KF

C) NaNO3

D) NH4Cl

E) NaF

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

A) H2SO4

B) HSO4–

C) H2SO3

D) H2SeO4

E) HSO3–

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

A) HClO

B) HClO3

C) HClO2

D) HClO4

E) HIO

46) In the gas phase reaction below, NH3 is acting as a(n) ________ base but not as a(n) ________ base.

A) Arrhenius, Br∅nsted-Lowry

B) Br∅nsted-Lowry, Lewis

C) Lewis, Arrhenius

D) Lewis, Br∅nsted-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 CO32- ?

A) CO22-

B) HCO22-

C) H2CO3

D) HCO3–

E) none of the above

3) The conjugate base of HSO4– is ________.

A) OH–

B) H2SO4

C) SO42-

D) HSO4+

E) H3SO4+

4) The conjugate base of H2PO4– is ________.

A) PO43-

B) H2PO4

C) H3PO4

D) HPO42-

E) none of the above

5) The conjugate acid of HSO4– is ________.

A) SO42-

B) H2SO4

C) HSO4+

D) H+

E) HSO3+

6) The conjugate acid of CH3NH2 is ________.

A) CH3NH2

B) CH3NH3+

C) CH3NH2+

D) CH3NH+

E) none of the above

7) What is the conjugate base of OH–?

A) O2

B) O–

C) H2O

D) O2-

E) H3O+

8) What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydronium ion?

A) 8.400

B) 5.600

C) 9.000

D) 3.980

E) 7.000

9) What is the pOH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydronium ion?

A) 8.400

B) 5.600

C) 9.000

D) 3.980

E) 7.000

10) What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?

A) 8.40

B) 5.60

C) 9.00

D) 3.98

E) 7.00

11) What is the pOH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?

A) 8.40

B) 5.60

C) 9.00

D) 3.98

E) 7.00

12) Calculate the pOH of a solution at 25.0 °C that contains 1.94 × 10–10 M hydronium ions.

A) 1.94

B) 4.29

C) 7.00

D) 14.0

E) 9.71

13) Calculate the pH of a solution at 25.0 °C that contains 1.94 × 10–10 M hydronium ions.

A) 1.94

B) 4.29

C) 7.00

D) 14.0

E) 9.71

14) Calculate the concentration (in M) of hydronium ions in a solution at 25.0 °C with a pOH of 4.223.

A) 5.98 × 10-5

B) 1.67 × 10–10

C) 1.67 × 104

D) 5.99 × 10–19

E) 1.00 × 10-7

15) Calculate the concentration (in M) of hydroxide ions in a solution at 25.0 °C with a pOH of 4.223.

A) 5.98 × 10-5

B) 1.67 × 10–10

C) 1.67 × 104

D) 5.99 × 10–19

E) 1.00 × 10-7

16) An aqueous solution contains 0.100 M NaOH at 25.0 °C. The pH of the solution is ________.

A) 0.100

B) 1.00

C) 13.00

D) 7.00

E) -1.00

17) An aqueous solution contains 0.150 M HCl at 25.0 °C. The pH of the solution is ________.

A) 0.150

B) 1.00

C) 13.00

D) 7.00

E) 0.82