Deck 16: Acids and Bases

Question 1

What is the conjugate acid of the hydroxide ion?

A) H₃O⁺
B) OH^-
C) H₃O
D) OH
E) H₂O

Answer 1

H₂O

Question 2

After a substance acting as a strong base reacts, what remains of the base?

A) a weaker base
B) a strong conjugate acid
C) a strong conjugate base
D) a strong acid
E) a weak conjugate acid

Answer 2

a weak conjugate acid

Question 3

After a substance acting as a strong acid reacts, what remains of the acid?

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

Answer 3

a weak conjugate base

Question 4

What is the name given to a substance that can act as a Brønsted acid or as a Brønsted base according to what it is reacting with?

A) hydrophilic
B) hydrophobic
C) amphoteric
D) isoprotic
E) isoelectronic

Question 5

What is the value of the equilibrium constant for the autoionization of water at 25°C?

A) 1.0 × 10^-7
B) 1.0 × 10^-14
C) 1.0 × 10¹⁴
D) 1.0 × 10⁷
E) 14

Question 6

In the reaction, HSO₄^-(aq) + OH^-(aq) SO₄^2-(aq) + H₂O(l), the conjugate acid-base pairs are

A) HSO₄^- and SO₄^2-; H₂O and OH^-.
B) HSO₄^- and H₃O⁺; SO₄^{2 -} and OH^-.
C) HSO₄^- and OH^-; SO₄^{2 -} and H₂O.
D) HSO₄^- and H₂O; OH ^- and SO₄^2-.
E) HSO₄^- and OH^-; SO₄^{2 -} and H₃O⁺.

Question 7

Identify the conjugate base of HPO₄^2- in the reaction HCO₃^- + HPO₄^2- H₂CO₃ + PO₄^3-

A) H₂O
B) HCO₃^-
C) H₂CO₃
D) PO₄^3-
E) None of these

Question 8

What is the conjugate base of NH₃?

A) NH₂
B) NH₂⁺
C) NH₂^-
D) NH₄
E) NH₄⁺

Question 9

What is the conjugate acid of the acetate ion?

A) CH₃O^2-
B) COOH
C) HC₂H₃O₂
D) H₂O
E) CH₄

Question 10

What is the concentration of H⁺ in a 0.025 M HCl solution?

A) 0
B) 0.013 M
C) 0.025 M
D) 0.050 M
E) 0.010 M

Question 11

What is the conjugate acid of NH₃?

A) NH₂
B) NH₂⁺
C) NH₂^-
D) NH₄
E) NH₄⁺

Question 12

What is the concentration of OH^- in a 0.083 M NaOH solution?

A) 0.083 M
B) 1.21 × 10^{-13 M}
C) 8.30 × 10^{-16 M}
D) 7 M
E) 8.30 × 10^{12 M}

Question 13

What is the name of a proton donor in an acid-base reaction?

A) Arrhenius acid
B) Arrhenius base
C) Brønsted acid
D) Brønsted base
E) Lewis base

Question 14

What is the conjugate base of water?

A) H₃O⁺
B) OH^-
C) H₃O
D) OH
E) H₂O₂

Question 15

What is the conjugate base of HSO₄^- in the reaction below? CO₃^2- + HSO₄^- HCO₃^- + SO₄^2-

A) HSO₄^-
B) CO₃^2-
C) OH^-
D) H₃O⁺
E) SO₄^2-

Question 16

What is [OH^-] for a solution at 25°C that has [H₃O⁺] = 2.35 × 10^{-3 M}?

A) 4.26 × 10^{-5 M}
B) 2.35 ×10^{-11 M}
C) 4.26 × 10^{-12 M}
D) 2.35 × 10^{-17 M}
E) 2.35 ×10^{-3 M}

Question 17

What is the conjugate acid of CO₃^2- in the reaction below? CO₃^2- + HSO₄^- HCO₃^- + SO₄^2-

A) HCO₃^-
B) HSO₄^-
C) OH^-
D) H₃O⁺
E) SO₄^2-

Question 18

What is the name of a proton acceptor in an acid-base reaction?

A) Arrhenius acid
B) Arrhenius base
C) Brønsted acid
D) Brønsted base
E) Lewis base

Question 19

Which of the following is the correct equilibrium expression for the autoionization of water?

A) K_w = [H₂O]²
B)
C) K_w = [OH][H₃O]
D) K_w = [OH^-][H₃O⁺]
E)

Question 20

What is the conjugate base of sulfuric acid?

A) HSO₄^-
B) H₃O⁺
C) OH^-
D) SO₄^2-
E) H₃SO₄⁺

Question 21

The substance NH₃ is considered to be

A) a weak acid.
B) a weak base.
C) a strong acid.
D) a strong base.
E) a neutral compound.

Question 22

What is the concentration of OH^- in a 1.0 × 10^{-3 M} Ba(OH)₂ solution?

A) 0.50 × 10^{-3 M}
B) 1.0 × 10^{-3 M}
C) 2.0 × 10^{-3 M}
D) 1.0 × 10^{-2 M}
E) 3.3 × 10^{-4 M}

Question 23

Which one of the following is a strong acid?

A) H₂CO₃
B) H₂SO₃
C) H₂SO₄
D) H₃PO₄
E) CH₃COOH

Question 24

What is the H⁺ ion concentration in a 2.1 × 10^{-4 M} Ca(OH)₂ solution?

A) 7.3 × 10^{-4 M}
B) 4.2 × 10^{-4 M}
C) 2.1 × 10^{-4 M}
D) 2.4 × 10^{-11 M}
E) 4.8 × 10^{-11 M}

Question 25

Which is the strongest acid?

A) HBrO₄
B) HBr
C) HBrO₂
D) HBrO
E) HBrO₃

Question 26

What is the [H₃O⁺] for a solution at 25°C that has pOH = 5.640?

A) 2.34 × 10^{-4 M}
B) 2.29 × 10^{-6 M}
C) 4.37 × 10^{-9 M}
D) 4.27 × 10^{-11 M}
E) 8.360 M

Question 27

Which one of the following is a strong acid?

A) CH₃COOH
B) H₂SO₃
C) NH₃
D) H₃PO₄
E) HClO₃

Question 28

Which is the formula for the hydronium ion?

A) OH^-
B) H₂O
C) H₃O⁺
D) H₃O^-
E) H₂O⁺

Question 29

What is the pOH of a 0.0085 M KOH solution?

A) 2.07
B) 4.85
C) 9.15
D) 11.93
E) 0.0085

Question 30

What is [OH^-] for a solution at 25°C that has [H₃O⁺] = 8.23 × 10^{-2 M}?

A) 8.23 × 10^{-2 M}
B) 1.22 × 10^{-6 M}
C) 8.23 × 10^{-12 M}
D) 1.22 × 10^{-13 M}
E) 8.23 × 10^{-16 M}

Question 31

Which one of the following is a strong base?

A) LiOH
B) CH₃COOH
C) NH₃
D) H₃PO₄
E) HClO₂

Question 32

What is the pH of a 0.014 M Ca(OH)₂ solution?

A) 1.85
B) 1.55
C) 12.15
D) 12.45
E) 15.85

Question 33

Acid strength increases in the series HCN < HF < HSO₄^-. Which of these species is the strongest base?

A) H₂SO₄
B) SO₄^2-
C) F^-
D) CN ^-
E) HSO₄^-

Question 34

The pH of a Ba(OH)₂ solution is 10.00. What is the H⁺ ion concentration of this solution?

A) 4.0 × 10^{-11 M}
B) 1.6 × 10^{-10 M}
C) 1.3 × 10^{-5 M}
D) 1.0 × 10^{-10 M}
E) 10.00 M

Question 35

Acid strength decreases in the series HI > HSO₄^-> HF > HCN. Which of these anions is the weakest base?

A) I^-
B) SO₄^2-
C) F^-
D) CN^-

Question 36

What is the pOH of a 0.025 M HI solution?

A) 0.025
B) 0.94
C) 1.60
D) 12.40
E) 10.31

Question 37

What is the pH of a 0.056 M HNO₃ solution?

A) 0.056
B) 1.25
C) 12.75
D) 2.88
E) 11.11

Question 38

What is the pH of a 0.050 M LiOH solution?

A) 1.30
B) 3.00
C) 11.00
D) 12.39
E) 12.70

Question 39

The substance HClO₄ is considered to be

A) a weak acid.
B) a weak base.
C) a strong acid.
D) a strong base.
E) a neutral compound.

Question 40

The substance (CH₃CH₂)₂NH is considered to be

A) a weak acid.
B) a weak base.
C) a strong acid.
D) a strong base.
E) a neutral compound.

Question 41

A 1.25 M solution of the weak acid HA is 9.2% dissociated. What is the pH of the solution?

A) 0.64
B) 0.94
C) 1.13
D) 2.16
E) -0.097

Question 42

Find the pH of a 0.135 M aqueous solution of periodic acid (HIO₄), for which K_a = 2.3 × 10^-2.

A) 1.25
B) 3.28
C) 1.17
D) 1.34
E) 1.64

Question 43

A 0.15 M solution of chloroacetic acid has a pH of 1.86. What is the value of K_a for this acid?

A) 7.2 × 10¹
B) 1.6 × 10^-1
C) 9.9 × 10^-2
D) 1.4 × 10^-3
E) 2.7 × 10^-4

Question 44

Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. What is the K_a for the acid?

A) 0.36
B) 2.4 × 10^-2
C) 7.8 × 10^-3
D) 1.5 × 10^-5
E) 1.9 × 10^-3

Question 45

Consider the weak bases below and their K_b values: C₆H₇O^{- K}_b = 1.3 × 10^-10
C₂H₅NH₂ K_b = 5.6 × 10^-4
C₅H₅N K_b = 1.7 ×10^-9
Arrange the conjugate acids of these weak bases in order of increasing acid strength.

A) C₅H₅NH⁺< C₆H₇OH < C₂H₅NH
B) C₆H₇OH < C₅H₅NH⁺ < C₂H₅NH
C) C₅H₅NH⁺< C₂H₅NH₃⁺ < C₆H₇OH
D) C₆H₇OH < C₂H₅NH₃⁺< C₅H₅NH⁺
E) C₂H₅NH₃⁺< C₅H₅NH⁺ < C₆H₇OH

Question 46

Which is the weakest acid?

A) HBrO₄
B) HBr
C) HBrO₂
D) HBrO
E) HBrO₃

Question 47

Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H₃O⁺] for a 0.20 M solution of picric acid?

A) 0.022 M
B) 0.052 M
C) 0.15 M
D) 0.20 M
E) 0.29 M

Question 48

Which is the weakest acid?

A) SO₄^2-
B) H₂SO₃
C) H₂SO₄
D) HSO₄^-
E) HSO₃^-

Question 49

What is the pH of a 0.20 M solution of NH₄Cl? [K_b(NH₃) = 1.8 × 10^-5]

A) 3.74
B) 4.98
C) 6.53
D) 9.02
E) 11.28

Question 50

Which is the strongest acid?

A) HBrO₃
B) HClO
C) HBrO₂
D) HBrO
E) HClO₃

Question 51

What is the pH of a 0.050 M triethylamine, (C₂H₅)₃N, solution? K_b for triethylamine is 5.3 × 10^-4.

A) 11.69
B) 8.68
C) 5.32
D) 2.31
E) 1.30

Question 52

Find the pH of a 0.20 M aqueous solution of dichloroacetic acid, for which K_a = 3.32 × 10^-2.

A) 0.75
B) 2.71
C) 1.05
D) 2.35
E) 1.18

Question 53

Formic acid, which is a component of some insect venoms, has a K_a = 1.8 × 10^-4. What is the [H₃O⁺] in a solution that is initially 0.10 M formic acid, HCOOH?

A) 4.2 × 10^{-3 M}
B) 8.4 × 10^{-3 M}
C) 1.8 × 10^{-4 M}
D) 1.8 × 10^{-5 M}
E) 1.8 × 10^{-6 M}

Question 54

Hydroxylamine, HONH₂, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has K_b = 9.1 × 10^-9. What is the pH of a 0.025 M HONH₂ solution?

A) 2.90
B) 4.82
C) 9.18
D) 9.91
E) 11.10

Question 55

Hard water deposits (calcium carbonate) have built up around your bathroom sink. Which of these substances would be most effective in dissolving the deposits?

A) ammonia
B) bleach (sodium hypochlorite)
C) lye (sodium hydroxide)
D) vinegar (acetic acid)

Question 56

Find the pH of a 0.183 M aqueous solution of hypobromous acid (HOBr), for which K_a = 2.06 × 10^-9.

A) 4.712
B) 8.686
C) 0.738
D) 4.576
E) 9.288

Question 57

Which is the weakest acid?

A) HBrO₃
B) HClO
C) HBrO₂
D) HBrO
E) HClO₃

Question 58

Farmers who raise cotton once used arsenic acid, H₃AsO₄, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K_a1 = 2.5 × 10^-4, K_a2 = 5.6 × 10^-8, and K_a3 = 3 × 10^-13. What is the pH of a 0.500 M solution of arsenic acid?

A) 0.85
B) 1.95
C) 3.90
D) 4.51
E) None of these choices is correct.

Question 59

Which is the strongest acid?

A) SO₄^2-
B) H₂SO₃
C) H₂SO₄
D) HSO₄^-
E) HSO₃^-

Question 60

The acid dissociation constant K_a equals 1.26 × 10^-2 for HSO₄^- and is 5.6 × 10^-10 for NH₄⁺. Which statement about the following equilibrium is correct? HSO₄^-(aq) + NH₃(aq) SO₄^2-(aq) + NH₄⁺(aq)

A) The reactants will be favored because ammonia is a stronger base than the sulfate anion.
B) The products will be favored because the hydrogen sulfate ion is a stronger acid than the ammonium ion.
C) Neither reactants nor products will be favored because all of the species are weak acids or bases.
D) The initial concentrations of the hydrogen sulfate ion and ammonia must be known before any prediction can be made.
E) This reaction is impossible to predict, since the strong acid and the weak base appear on the same side of the equation.

Question 61

For H₃PO₄, K_a1 = 7.3 × 10^-3, K_a2 = 6.2 × 10^-6, and K_a3 = 4.8 × 10^-13. A 0.10 M aqueous solution of Na₃PO₄ therefore would be ________.

A) neutral
B) weakly basic
C) weakly acidic
D) strongly acidic
E) strongly basic

Question 62

A solution is prepared by adding 0.10 mol of lithium nitrate, LiNO₃, to 1.00 L of water. Which statement about the solution is correct?

A) The solution is basic.
B) The solution is neutral.
C) The solution is weakly acidic.
D) The solution is strongly acidic.
E) The values for K_a and K_b for the species in solution must be known before a prediction can be made.

Question 63

A student adds 0.1 mol of oxalic acid and 0.1 mol of sodium dihydrogen phosphate to enough water to make 1.0 L of solution. The following equilibrium is established with the concentrations of the products greater than the concentrations of the reactants. Which of the statements about the equilibrium system is correct? H₂C₂O₄(aq) + H₂PO₄^-(aq) HC₂O₄^-(aq) + H₃PO₄(aq)

A) Oxalic acid is a weaker acid than phosphoric acid.
B) The hydrogen oxalate anion, HC₂O₄^-, is a stronger base than the dihydrogen phosphate anion, H₂PO₄^-.
C) Phosphoric acid is a weaker acid than oxalic acid.
D) The dihydrogen phosphate anion, H₂PO₄^-, is a stronger acid than oxalic acid.
E) Water is a stronger acid than either oxalic or phosphoric acids.

Question 64

Ammonium chloride is used as an electrolyte in dry cells. Which statement about a 0.10 M solution of NH₄Cl is correct?

A) The solution is weakly basic.
B) The solution is strongly basic.
C) The solution is neutral.
D) The solution is acidic.
E) The values for K_a and K_b for the species in solution must be known before a prediction can be made.

Question 65

A solution is prepared by adding 0.10 mol of iron(III) nitrate, Fe(NO₃)₃, to 1.00 L of water. Which statement about the solution is correct?

A) The solution is basic.
B) The solution is neutral.
C) The solution is acidic.
D) The value of K_a for the species in solution must be known before a prediction can be made.
E) The value of K_b for the species in solution must be known before a prediction can be made.

Question 66

Which is the strongest base?

A) CH₃NH₂, K_b = 4.4 × 10^-4
B) C₅H₅N, K_b = 1.7 × 10^-9
C) H₂NCONH₂, K_b = 1.5 × 10^-14
D) NH₃, K_b = 1.8 × 10^-5
E) C₂H₅NH₂, K_b = 5.6 × 10^-4

Question 67

What is the pH of a 0.0100 M sodium benzoate solution? K_b (C₇H₅O₂^-) = 1.5 × 10^-10

A) 0.38
B) 12.00
C) 10.91
D) 8.09
E) 13.62

Question 68

What is the value of K_b for the cyanide anion, CN^-? K_a(HCN) = 6.2 × 10^-10

A) 1.6 × 10^-4
B) 1.6 × 10^-5
C) 3.8 × 10^-4
D) 3.8 × 10^-5
E) 6.2 × 10⁴

Question 69

The reaction of a strong acid with water results in

A) a weak conjugate acid.
B) a strong conjugate base.
C) a weak conjugate base.
D) a strong base.
E) pure water.

Question 70

What is the value of K_b for the formate anion, HCOO^- ? K_a (HCOOH) = 2.1 × 10^-4

A) -2.1 × 10^-4
B) 2.1 × 10^-4
C) 6.9 × 10^-6
D) 4.8 × 10^-11
E) 2.1 × 10^-18

Question 71

Which one of these salts will form an acidic solution upon dissolving in water?

A) LiBr
B) NaF
C) NH₄Br
D) KOH
E) NaCN

Question 72

Which one of these salts will form a basic solution upon dissolving in water?

A) NaCl
B) NaNO₂
C) NH₄NO₃
D) KBr
E) AlCl₃

Question 73

Which aqueous solution has the highest pH?

A) 0.1 M CH₃COOH, pK_a = 4.7
B) 0.1 M CuCl₂, pK_a = 7.5
C) 0.1 M H₃C₆H₅O₇, pK_a = 3.1
D) 0.1 M ZnCl₂, pK_a = 9.0
E) pure water

Question 74

Which is the strongest acid?

A) HBrO₃
B) HFO₃
C) HIO₃
D) HClO₃
E) All are of equal strength.

Question 75

A solution is prepared by adding 0.10 mol of potassium chloride, KCl, to 1.00 L of water. Which statement about the solution is correct?

A) The solution is basic.
B) The solution is neutral.
C) The solution is acidic.
D) The solution is a strong oxidant.
E) The values for K_a and K_b for the species in solution must be known before a prediction can be made.

Question 76

A solution is prepared by adding 0.10 mol of sodium fluoride, NaF, to 1.00 L of water. Which statement about the solution is correct?

A) The solution is basic.
B) The solution is neutral.
C) The solution is acidic.
D) The concentrations of fluoride ions and sodium ions are equal.
E) The concentrations of hydronium ions and hydroxide ions are equal.

Question 77

Calculate the pH of a 0.021 M NaCN solution. [K_a(HCN) = 4.9 × 10^-10]

A) 1.68
B) 3.19
C) 4.69
D) 9.31
E) 10.81

Question 78

Calculate the concentration of malonate ion (C₃H₂O₄^2-) in a 0.200 M solution of malonic acid (C₃H₄O₄). (For malonic acid, K_a1 = 1.4 × 10^-3, K_a2 = 2.0 × 10^-6.)

A) 2.8 × 10^{-4 M}
B) 0.016 M
C) 1.8 × 10^{-4 M}
D) 1.4 × 10^{-3 M}
E) 2.0 × 10^{-6 M}

Question 79

For H₃PO₄, K_a1 = 7.3 × 10^-3, K_a2 = 6.2 × 10^-6, and K_a3 = 4.8 × 10^-13. A 0.10 M aqueous solution of NaH₂PO₄ therefore would be ________.

A) neutral
B) weakly basic
C) weakly acidic
D) strongly acidic
E) strongly basic

Question 80

What are the products of hydrolysis of NH₄Cl?

A) NH₄⁺ + HCl
B) NH₃ + OH^- + HCl
C) NH₃ + H₃O⁺ + Cl^-
D) NH₄OH + HCl
E) No hydrolysis occurs.