Deck 16: Acid-Base Equilibria

Question 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

Answer 1

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

Question 2

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

Answer 2

1.0 × 10^-7

Question 3

Which one of the following statements regarding K_w is false?

A)pK_w is 14.00 at 25 °C.
B)The value of K_w is always 1.0 × 10^-14.
C)K_w changes with temperature.
D)The value of K_w shows that water is a weak acid.
E)K_w is known as the ion product of water.

Answer 3

The value of K_w is always 1.0 × 10^-14.

Question 4

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

A)HOAc
B)HCHO₂
C)HClO
D)HF
E)HOAc and HCHO₂

Question 5

The hydride ion, ,is a stronger base than the hydroxide ion,O .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)

Question 6

Of the following acids,________ is a strong acid.

A)HNO₂
B)H₂CO₃
C)HNO₃
D)HClO
E)HF

Question 7

The K_a of hypochlorous acid (HClO)is 3.0 × 10^-8 at .What is the percent ionization of hypochlorous acid in a aqueous solution of HClO at

A)4.5 × 10^-8
B)14
C)2.1 × 10^-5
D)0.14
E)1.4 × 10^-3

Question 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

Question 9

The magnitude of K_w 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

Question 10

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

Question 11

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

Question 12

Which one of the following is the weakest acid?

A)HF (K_a = 6.8 × 10^-4)
B)HClO (K_a = 3.0 × 10^-8)
C)HNO₂ (K_a = 4.5 × 10^-4)
D)HCN (K_a = 4.9 × 10^-10)
E)Acetic acid (K_a = 1.8 × 10^-5)

Question 13

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

Question 14

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

Question 15

A substance that is capable of acting as both an acid and as a base is ________.

A)autosomal
B)conjugated
C)amphiprotic
D)saturated
E)miscible

Question 16

A Br∅nsted-Lowry acid is defined as a substance that ________.

A)increases K_a 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

Question 17

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

A)HNO₂
B)H₂SO₄
C)HNO₃
D)HClO₄
E)HCl

Question 18

Classify the following compounds as weak acids (W)or strong acids (S): hydrocyanic acid hydrofluoric acid hydrobromic acid

A)S W W
B)S S S
C)W W S
D)W S S
E)W S W

Question 19

Of the following,________ is a weak acid.

A)HF
B)HCl
C)HBr
D)HNO₃
E)HClO₄

Question 20

Classify the following compounds as weak acids (W)or strong acids (S): hydrobromic acid hydrochloric acid hydrofluoric acid

A)W W W
B)S S S
C)S W W
D)W S S
E)S S W

Question 21

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 HN
C)a solution with a pOH of 12.0
D)pure water
E)a 1 × 10^-3 M solution of N Cl

Question 22

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 HN
C)a solution with a pOH of 12.0
D)pure water
E)a 1 × 10^-3 M solution of N Cl

Question 23

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

Question 24

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

A)OAc^-
B)C₇H₅O₂^-
C)NO₂^-
D)
E)OAc^- and C₇H₅O₂^-

Question 25

Classify the following compounds as weak bases (W)or strong bases (S): methylamine carbonate ion potassium ion

A)S S S
B)S W W
C)W S S
D)W W W
E)W S W

Question 26

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⁺

Question 27

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

A)NH₄⁺
B)C₅H₅NH⁺
C)NH₃CH₂CH₃⁺
D)H₃NOH⁺
E)NH₄⁺ and NH₃CH₃⁺

Question 28

Which of the following ions will act as a strong base in water?

A)HS^-
B)F^-
C)NO₂^-
D)ClO^-
E)None of the above will act as a strong base in water.

Question 29

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

A)OAc^-
B)C₇H₅O₂^-
C)NO₂^-
D)
E)OAc- and C₇H₅

Question 30

An aqueous solution of a particular compound has pH = 7.46.The compound is ________.

A)a weak base
B)a weak acid
C)a strong acid
D)a strong base
E)a salt

Question 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

Question 32

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^-

Question 33

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^-

Question 34

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

Question 35

Ammonia is a ________.

A)weak acid
B)strong base
C)weak base
D)strong acid
E)salt

Question 36

A- is a weak base.Which equilibrium corresponds to the equilibrium constant K_a 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) HOA^2- (aq)

Question 37

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.

Question 38

Classify the following compounds as weak bases (W)or strong bases (S): ammonia fluoride ion sodium ion

A)S S S
B)S W W
C)W W W
D)W S S
E)W S W

Question 39

Classify the following compounds as weak acids (W)or strong acids (S): nitric acid perchloric acid chloric acid

A)W W W
B)W S S
C)S S S
D)S W W
E)W S W

Question 40

HA is a weak acid.Which equilibrium corresponds to the equilibrium constant K_b 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) HOA^2- (aq)

Question 41

What is the pH of an aqueous solution at 25.0 °C that contains 1.35 × 10^-8 M hydroxide ion?

A)7.87
B)8.00
C)6.13
D)1.35
E)7.00

Question 42

The conjugate base of CH₃NH₃⁺ is ________.

A)CH₃NH₂⁺
B)CH₃NH₂^-
C)CH₃NH⁺
D)CH₃NH₂
E)none of the above

Question 43

What is the conjugate acid of HCO₃^-?

A)CO₂^2-
B)H₂CO₃
C)HCO₂^2-
D)CO₃^2-
E)none of the above

Question 44

Calculate the pH of a solution at 25.0 °C that contains 2.95 × 10^-12 M hydronium ions.

A)2.95
B)11.53
C)7.00
D)12.00
E)2.47

Question 45

Of the following substances,an aqueous solution of ________ will form basic solutions. NH₄Br Pb(NO₃)₂ K₂CO₃ NaF

A)NH₄Br, Pb(NO₃)₂
B)K₂CO₃, NH₄Br
C)NaF only
D)NaF, K₂CO₃
E)NH₄Br only

Question 46

The conjugate base of HSO₄^- is ________.

A)H₂SO₄
B)HSO₄⁺
C)H⁺
D)SO₄^2-
E)HSO₃⁺

Question 47

In the gas phase reaction below,NH₃ is acting as a(n)________.

A)Br∅nsted-Lowry acid
B)Br∅nsted-Lowry base
C)Lewis base
D)Lewis acid
E)Arrhenius acid

Question 48

A 0.5 M solution of ________ has a pH of 7.0.

A)K₂S
B)KF
C)KNO₃
D)NH₄Br
E)NaF

Question 49

The conjugate acid of SO₄^2- is ________.

A)OH^-
B)H₂SO₄
C)HSO₄^-
D)HSO₄^2-
E)H₃SO₄⁺

Question 50

What is the conjugate acid of OH^-?

A)O₂
B)H₂O
C)O^-
D)O^2-
E)H₃O⁺

Question 51

What is the pH of an aqueous solution at 25.0 °C that contains 2.50 × 10^-4 M hydronium ion?

A)10.4
B)4.00
C)2.50
D)3.60
E)7.00

Question 52

Calculate the concentration (in M)of hydronium ions in a solution at 25.0 °C with a pOH of 3.58.

A)2.63 × 10^-4
B)2.63 × 10¹⁰
C)3.80 × 10^-11
D)3.80 × 10³
E)1.00 × 10^-7

Question 53

What is the conjugate acid of NH₂^-?

A)NH₂⁺
B)NH₃⁺
C)NH₄⁺
D)NH₃
E)NH₄OH

Question 54

What is the pOH of an aqueous solution at 25.0 °C that contains 1.35 × 10^-8 M hydroxide ion?

A)6.13
B)7.87
C)1.35
D)8.00
E)7.00

Question 55

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

A)KCN, K_a of HCN = 4.0 × 10^-10
B)NH₄NO₃, K_b of NH₃ = 1.8 × 10^-5
C)NaOAc, K_a of HOAc = 1.8 × 10^-5
D)NaClO, K_a of HClO = 3.2 × 10^-8
E)NaHS, K_b of HS^- = 1.8 × 10^-7

Question 56

What is the pOH of an aqueous solution at 25.0 °C that contains 2.50 × 10^-4 M hydronium ion?

A)3.60
B)4.00
C)2.50
D)10.4
E)7.00

Question 57

Calculate the pOH of a solution at 25.0 °C that contains 2.95 × 10^-12 M hydronium ions.

A)12.00
B)2.95
C)7.00
D)2.47
E)11.53

Question 58

Which of the following acids will be the strongest?

A)H₂SO₄
B)HSO₄^-
C)H₂SO₃
D)H₂SeO₄
E)HSO₃^-

Question 59

Of the following,which is the strongest acid?

A)HClO
B)HClO₃
C)HClO₂
D)HClO₄
E)HIO

Question 60

The conjugate base of HPO₄^2- is ________.

A)PO₄^3-
B)H₂PO₄
C)H₃PO₄
D)H₂PO₄^-
E)none of the above

Question 61

An aqueous solution of NaF is prepared by dissolving 0.350 mol of NaF in sufficient water to yield 1.0 L of solution.The pH of the solution was 8.93 at 25.0 °C.The K_b of F^- is ________.

A)1.2 × 10^-5
B)2.1 × 10^-10
C)6.9 × 10^-9
D)2.8 × 10^-12
E)9.9 × 10^-2

Question 62

The pH of a 0.60 M aqueous solution of formic acid,HCHO₂,at 25.0 °C is 1.98.What is the value of K_a for formic acid?

A)2.0 × 10^-5
B)1.8 × 10^-4
C)6.0 × 10^-5
D)3.5 × 10^-4
E)none of the above

Question 63

An aqueous solution contains 0.500 M NaOH at 25.0 °C.The pH of the solution is ________.

A)0.500
B)13.70
C)0.301
D)7.00
E)13.50

Question 64

An aqueous basic solution has a concentration of 0.050 M and K_b is 4.4 × 10^-4.What is the concentration of hydronium ion in this solution (M)?

A)2.2 × 10^-13
B)2.2 × 10^-12
C)2.9 × 10^-13
D)0.050
E)4.5 × 10^-13

Question 65

The K_a of hypochlorous acid (HClO)is What is the pH at 25.0 °C of an aqueous solution that is in

A)+2.45
B)-2.45
C)-9.22
D)+9.22
E)+4.61

Question 66

HZ is a weak acid.An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution.The pH of the solution was 4.93 at 25.0 °C.The K_a of HZ is ________.

A)1.2 × 10^-5
B)6.9 × 10^-9
C)1.4 × 10^-10
D)9.9 × 10^-2
E)2.8 × 10^-12

Question 67

Calculate the concentration (in M)of hydroxide ions in a solution at 25.0 °C with a pOH of 3.58.

A)2.63 × 10¹⁰
B)3.80 × 10^-11
C)1.00 × 10^-7
D)3.80 × 10³
E)2.63 × 10^-4

Question 68

The K_a of acetic acid (HC₂H₃O₂)is What is the pH at 25.0 °C of an aqueous solution that is in

A)+2.87
B)-2.87
C)-11.13
D)+11.13
E)+6.61

Question 69

The pH of a 0.25 M aqueous solution of hydrofluoric acid,HF,at 25.0 °C is 2.03.What is the value of K_a for HF?

A)2.0 × 10^-9
B)1.1 × 10^-9
C)6.0 × 10^-5
D)3.5 × 10^-4
E)none of the above

Question 70

The pH of a 0.55 M aqueous solution of hypobromous acid,HBrO,at 25.0 °C is 4.48.What is the value of K_a for HBrO?

A)2.0 × 10^-9
B)1.1 × 10^-9
C)6.0 × 10^-5
D)3.3 × 10^-5
E)3.0 × 10⁴

Question 71

A 0.10 M aqueous solution of the weak base B at 25.0 °C has a pH of 8.00.The value of K_b for B is ________.

A)1.0 × 10^-15
B)1.0 × 10^-11
C)1.0 × 10^-6
D)1.0 × 10^-12
E)none of the above

Question 72

The pOH of a 0.10 M solution of a weak base is 4.18.What is the K_b for this base?

A)8.8 × 10^-8
B)2.1 × 10^-4
C)6.6 × 10^-4
D)4.4 × 10^-8
E)2.0 × 10^-5

Question 73

The pH of a 0.25 M aqueous solution ammonia,NH₃,at 25.0 °C is 9.50.What is the value of K_b for NH₃?

A)2.5 × 10^-1
B)4.0 × 10^-19
C)4.0 × 10^-9
D)3.2 × 10^-5
E)none of the above

Question 74

The acid-dissociation constants of sulfurous acid (H₂SO₃)are K_a1 = 1.7 × 10^-2 and at 25.0 °C.Calculate the pH of a 0.163 M aqueous solution of sulfurous acid.

A)4.53
B)1.28
C)1.86
D)6.21
E)1.93

Question 75

Determine the pH of a 0.35 M aqueous solution of CH₃NH₂ (methylamine).The K_b of methylamine is .

A)10.00
B)3.86
C)12.09
D)1.96
E)13.24

Question 76

A 0.14 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 3.15.The value of K_a for HA is ________.

A)7.08 × 10^-4
B)3.58 × 10^-6
C)5.01 × 10^-7
D)7.02 × 10^-8
E)none of the above

Question 77

An aqueous solution contains 0.390 M HCl at 25.0 °C.The pH of the solution is ________.

A)0.41
B)0.390
C)13.61
D)13.59
E)7.00

Question 78

An aqueous basic solution has a concentration of 0.050 M and K_b is 4.4 × 10^-4.What is the concentration of hydroxide ion in this solution (M)?

A)2.2 × 10^-5
B)4.5 × 10^-3
C)2.9 × 10^-3
D)4.7 × 10^-3
E)0.050

Question 79

The acid-dissociation constants of phosphoric acid (H₃PO₄)are = 7.5 × 10^-3, and K_a3 = 4.2 × 10^-13 at 25.0 °C.What is the pH of a 2.5 M aqueous solution of phosphoric acid?

A)1.82
B)0.40
C)2.51
D)0.86
E)0.13

Question 80

A 0.22 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 4.15.The value of K_a for HA is ________.

A)7.1 × 10^-5
B)3.2 × 10^-4
C)2.2 × 10^-1
D)2.3 × 10^-8
E)3.2 × 10⁴