Deck 15: Acids and Bases

Question 1

Carboxylic acids have the formula

A) R-CH₃
B) R-CHO
C) R-COOH
D) R-NH₂
E) R-OH

Answer 1

R-COOH

Question 2

In terms of acid strength, which acid does not belong in a category with the others?

A) HNO₂
B) HClO₄
C) HCOOH
D) HF
E) H₂SO₃

Answer 2

HClO₄

Question 3

Which reaction illustrates water acting as a base?

A) Cu(H₂O)₄²⁺ + 4 NH₃ Cu(NH₃)₄²⁺ + 4 H₂O
B) H₂CO₃ H₂O + CO₂
C) NH₃ + H₂O NH₄⁺ + OH^-
D) H₂PO₄^- + H₂O OH^- + H₃PO₄
E) HSO₄^- + H₂O H₃O⁺ + SO₄^2-

Answer 3

HSO₄^- + H₂O H₃O⁺ + SO₄^2-

Question 4

A Bronsted-Lowry base must have a(n) ____.

A) atom that does not obey the octet rule
B) atom with an unshared pair of electrons
C) nitrogen atom
D) amphiprotic atom
E) oxygen atom

Question 5

A Bronsted-Lowry acid is always

A) a highly dissociated acid
B) a weak acid
C) both an acceptor and donor of hydrogen ions
D) a donor of one or more hydrogen ions
E) a molecule or ion in which hydrogen is attached to an oxygen atom

Question 6

Which cannot act as a Bronsted-Lowry acid?

A) HPO₄^2-
B) H₃O⁺
C) CH₃COO^-
D) CH₃NH₃⁺
E) HCOOH

Question 7

The conjugate base of NH₃ is ____.

A) H₂O
B) OH^-
C)
D) NH₄OH
E)

Question 8

Bronsted-Lowry acids ____ and Bronsted-Lowry bases ____.

A) generate H₃O⁺ ions in aqueous solution; generate OH^- ions in aqueous solutions
B) accept protons; generate OH^- ions in aqueous solutions
C) generate OH^- ions in aqueous solution; generate H₃O⁺ ions in aqueous solutions
D) generate H₃O⁺ ions in aqueous solution; donate protons in aqueous solutions
E) donate protons; accept protons in aqueous solutions

Question 9

Which pair of substances represents a conjugate acid-base pair?

A) CH₃COO^- and H₂O
B) H₃O⁺ and OH^-
C) CH₃COOH and CH₃COO^-
D) CH₃COOH and H₃O⁺
E) CH₃COOH and OH^-

Question 10

Because water can act as a Bronsted-Lowry acid or base, it is said to be ____.

A) amphiphilic
B) amphihydrous
C) amphiphobic
D) amphiprotic
E) amphoteric

Question 11

Amines have the general formula

A) R-CHO
B) CH₃-(CH₂)_n-CH₃
C) R-COOH
D) R-NH₂
E) R-OH

Question 12

In this reaction

A) NH₃ acts as a base and OH^- as an acid.
B) H₂O acts as an acid and NH₃ as a base.
C) H₂O acts as a base and NH₄⁺ as an acid.
D) H₂O acts as an acid and NH₄⁺ as a base.
E) NH₃ acts as an acid and OH^- as a base.

Question 13

In terms of base strength, which base does not belong in a category with the others?

A) Ba(OH)₂
B) NaOH
C) Sr(OH)₂
D) LiOH
E) NH₄OH

Question 14

Which pair of substances does not represent a conjugate acid-base pair?

A) CH₃COOH and CH₃COO^-
B) CH₃NH₃⁺ and CH₃NH₂
C) H₂SO₃ and HSO₄^-
D) HPO₄^2- and PO₄^3-
E) HCOOH and HCOO^-

Question 15

The reaction between acetic acid (CH₃COOH) and water is written as

A) CH₃COOH + H₂O CH₂COOH^- + H₃O⁺
B) CH₃COOH + H₂O CH₃COO^- + OH^-
C) CH₃COOH + H₂O CH₃COOH₂⁺ + OH^-
D) CH₃COOH + H₂O CH₃COO^- + H₃O⁺
E) CH₃COOH + H₂O CH₃CO^- + OH^- + H₂O

Question 16

The product of the reaction between methylamine, CH₃NH₂, and hydrochloric acid are

A) CH₄NH₂⁺ and Cl^-
B) CH₃NH^- and H₂Cl⁺
C) CH₃NH₃⁺ and Cl^-
D) CH₃NH₃^- and Cl⁺
E) CH₃NH₄²⁺ and 2Cl^-

Question 17

Which substance can act as a Bronsted-Lowry base, but not as a Bronsted-Lowry acid?

A) HPO₄^2-
B) H₂O
C) NH₄⁺
D) PO₄^3-
E) HSO₄^-

Question 18

Which substance cannot act as a Bronsted-Lowry base?

A) OH^-
B) CH₃NH₂
C) NH₄⁺
D) NH₃
E) HSO₄^-

Question 19

Methylamine, CH₃NH₂, acts as a weak base in water. The products of the reaction are ____ and ____.

A) OH^- and CH₃NH₃⁺
B) H₃O⁺ and CH₃NH₃⁺
C) H₃O⁺ and OH^-
D) OH^- and CH₃NH^-
E) H₃O⁺ and CH₃NH^-

Question 20

Which factor does not contribute to the acidity of the hydrogen atom in the carboxylic acid functional group?

A) the attraction of the O atoms in the carboxylic acid group for the electrons in the O-H bond
B) resonance stabilization of the resulting anion
C) the electronegativity of the C atom
D) the lack of polarity in the C-H bonds in the rest of the molecule
E) the electronegativity of the O that is bonded to the H

Question 21

One water molecule can donate a proton to another in a process called ____; the equilibrium constant expression for this reaction is ____.

A) neutralization;
B) autoionization;
C) protonation;
D) hydrolysis;
E) autoionization; K_w = [H₃O⁺][OH^-]

Question 22

In an acidic solution at 25 ^$\circ$ C, which of the following is not true?

A) [H₃O⁺] > 1.0 × 10^-7
B) [H₃O⁺] > [OH^-]
C) [OH^-] < 1.0 × 10^-7
D) [H₃O⁺][OH^-] > 1.0 × 10^-7
E) [H₃O⁺][OH^-] < 1.0 × 10^-7

Question 23

An acidic solution is diluted until [H₃O⁺] is exactly half as much as before. The pH of the solution is now ____ than before.

A) 2.00 higher
B) 0.69 higher
C) 0.30 lower
D) 0.30 higher
E) 2.00 lower

Question 24

Classify each compound as a carboxylic acid or an amine, in the order given.

A) acid, acid, acid
B) acid, amine, acid
C) amine, amine, acid
D) amine, acid, amine
E) acid, acid, amine

Question 25

K_w for water

A) decreases as the temperature increases
B) increases as the temperature increases
C) is equal to 1.0 × 10^-14 at all temperatures
D) is equal to 1.0 × 10¹⁴ at all temperatures
E) none of these are correct

Question 26

Calculate the pH of a solution where [OH^-] = 4.6 × 10^-4. Is this solution acidic or basic?

A) 3.34; acidic
B) 3.34; basic
C) 9.40; basic
D) 10.66; acidic
E) 10.66; basic

Question 27

In a 1.2 M solution of HClO₄, a strong acid, [H₃O⁺] = ____, and [OH^-] = ____.

A) 1.0 × 10^-7 M; 1.0 × 10^-7 M
B) 8.3 × 10^-15 M; 1.0 × 10^-14 M
C) 8.3 × 10^-15 M; 1.2 M
D) 1.2 M; 8.3 × 10^-15 M
E) 1.2 M; 1.2 M

Question 28

The acid ionization constant expression for the ionization of the hydrogen sulfate ion, , in aqueous solution is

A)
B)
C)
D)
E)

Question 29

The larger the value of K_a

A) the less highly dissociated the acid and the weaker the acid
B) the less highly dissociated the acid and the stronger the acid
C) the more highly dissociated the acid and the weaker the acid
D) the more highly dissociated the acid and the stronger the acid
E) the answer depends on whether the acid is strong or weak

Question 30

In a basic solution at 25 ^$\circ$ C,

A) [H₃O⁺] > 1.0 × 10^-7.
B) [H₃O⁺] > [OH^-].
C) [OH^-] > 1.0 × 10^-7.
D) [H₃O⁺][OH^-] > 1.0 × 10^-14.
E) [H₃O⁺][OH^-] < 1.0 × 10^-14.

Question 31

A wine sample had a pH of 3.52. This corresponds to [H₃O⁺] =

A) 3.3 × 10^-11 M.
B) 3.0 × 10^-4 M.
C) 5.2 × 10^-4 M.
D) 5.2 × 10^-3 M.
E) 3.3 × 10^-3 M.

Question 32

As the pH of a solution rises, [H₃O⁺] ____, pOH ____, and [OH^-] ____.

A) rises; falls; rises
B) falls; rises; falls
C) falls; falls; rises
D) rises; falls; falls
E) falls, falls, falls

Question 33

If the pH of a solution is raised from 6.27 to 7.57

A) the solution has gone from acidic to basic
B) [H₃O⁺] has increased by a factor of 10
C) [OH^-] has increased by a factor of 10
D) the new [OH^-] = 2.7 × 10^-8
E) the new [H₃O⁺] = 5.4 × 10^-7

Question 34

A solution is not neutral. Which one of these statements is true?

A) [H₃O⁺] = 1.0 × 10^-7 M
B) [H₃O⁺] = [OH^-]
C) [H₃O⁺][OH^-] = 1.0 × 10^-7
D) [OH^-] = 1.0 × 10^-7 M
E) [H₃O⁺][OH^-] = 1.0 × 10^-14

Question 35

In a 1.2 M solution of KOH, a strong base, [H₃O⁺] = ____, and [OH^-] = ____.

A) 1.0 × 10^-7 M; 1.0 × 10^-7 M
B) 8.3 × 10^-15 M; 1.0 × 10^-14 M
C) 8.3 × 10^-15 M; 1.2 M
D) 1.2 M; 8.3 × 10^-15 M
E) 1.2 M; 1.2 M

Question 36

Phenolphthalein is an acid-base indicator that is colorless in its acid form and pink in its basic form, changing at pH = 8.5. Bromcresol green is yellow in its acidic form and blue in its basic form, changing at pH = 4.8. A solution is colorless in phenolphthalein and blue in bromcresol green. Therefore we can conclude that the pH of the solution is ____.

A) exactly 7.0
B) greater than 8.5
C) between 7.0 and 8.5
D) between 4.8 and 8.5
E) less than 4.8

Question 37

For the dissociation of a very weak acid, HA, in water

A) K_a = [HA] [H₃O⁺] [A^-]
B) K_a = [H₃O⁺] [A^-]
C) K_a = [H₃O⁺] [A^-] / [H₂O]
D) K_a = [HA] / [A^-] [H₃O⁺]
E) K_a = [H₃O⁺] [A^-] / [HA]

Question 38

Arrange the solutions in order of increasing acidity:

A) I < IV < II < III
B) II < IV < III < I
C) III < II < IV < I
D) IV < I < II < III
E) III < II < I < IV

Question 39

Which condition represents the most acidic solution?

A) [H₃O⁺] = .010 M
B) [OH^-] = 1.0 × 10^-13 M
C) pH = 3.6
D) [OH^-] = 1.0 × 10^-10 M
E) pOH = 8.3

Question 40

If the hydrogen ion concentration of a solution is increased by a factor of 4, the pH is

A) raised by 4 pH units
B) raised by 0.3 pH units
C) lowered by 2 pH units
D) lowered by 0.6 pH units
E) lowered by 0.25 pH units

Question 41

Ammonia is a weak base and acetic acid is a weak acid. Which statement is true of a solution of ammonium acetate?

A) It is strongly acidic
B) It is weakly acidic
C) It is neutral
D) It is weakly basic
E) We cannot predict its acid-base properties without more information

Question 42

Calculate the pH of a 0.051 M solution of sodium lactate. The K_a for lactic acid is 1.4 × 10^-4.

A) 1.29
B) 2.57
C) 8.28
D) 11.43
E) 12.71

Question 43

The reaction between the ion of a weak acid or a weak base and water is called a(n) ____ reaction.

A) autoionization
B) hydrolysis
C) decomposition
D) neutralization
E) proteomic

Question 44

Two common polyprotic acids are

A) sulfuric acid and perchloric acid
B) sulfuric acid and nitric acid
C) sulfuric acid and phosphoric acid
D) perchloric acid and nitric acid
E) nitric acid and phosphoric acid

Question 45

The value of the ionization constant for a weak acid HA is 4.2 × 10^-7. What is the pH of a 0.35 M solution of this acid?

A) 6.83
B) 6.38
C) 3.42
D) 3.19
E) 2.96

Question 46

Which salt forms a neutral solution when dissolved in water?

A) LiF
B) K₃PO₄
C) NH₄ClO₄
D) NaOCl
E) NaNO₃

Question 47

Consider a 0.50 M solution of HNO₂, a weak acid with K_a = 4.5 × 10^-4. Which statement is true?

A) [H₃O⁺] = 0.50 M.
B) The acid is mostly ionized.
C) pH = 3.35.
D) pH = 0.32.
E) pH > 0.32.

Question 48

In a neutral polyprotic acid, the value of K_a2 will be ____ the value of K_a1 because ____.

A) smaller than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule
B) larger than; it is more difficult to remove a hydrogen ion from an anion than from a neutral molecule
C) larger than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule
D) smaller than; it is more difficult to remove a hydrogen ion from an anion than from a neutral molecule
E) the same as; both hydrogen ions are bonded to the same anion

Question 49

Typically, for a weak acid and its conjugate base

A) K_a / K_b = 1.0 × 10^-14
B) K_a × K_b = 1.0 × 10^-14
C) K_a / K_b = 1.0
D) K_a × K_b = 1.0
E) K_a × K_b = 14

Question 50

Which compound is the most acidic?

A) GeH₄
B) H₂Se
C) HBr
D) AsH₃
E) H₂O

Question 51

Which substance is a Lewis acid but not a Bronsted-Lowry acid?

A) acetic acid
B) NH₄⁺(aq)
C) HCO₃^-(aq)
D) CO₂
E) CO₃^2-

Question 52

The poison strychnine is a weakly basic compound with K_b = 1.8 × 10^-6. What is the pH of a 0.058 M solution of strychnine?

A) 3.49
B) 7.30
C) 8.26
D) 10.51
E) 12.76

Question 53

Which of the following salts forms a basic solution when dissolved in water?

A) NH₄ClO₄
B) (NH₄)₂NO₃
C) NaClO₄
D) LiCH₃COO
E) NaCl

Question 54

The pH of a solution of a 0.15 M solution of HOCl is 4.14. What is the K_a for HOCl?

A) 5.7 × 10^-2
B) 8.8 × 10^-3
C) 4.8 × 10^-4
D) 7.2 × 10^-5
E) 3.5 × 10^-8

Question 55

Ammonia is a weak base and perchloric acid is a strong acid. Which statement is true of a solution of ammonium perchlorate?

A) It is strongly acidic
B) It is weakly acidic
C) It is neutral
D) It is weakly basic
E) We cannot predict its acid-base properties without more information

Question 56

Which of the following salts forms an acidic solution when dissolved in water?

A) LiF
B) K₃PO₄
C) NH₄ClO₄
D) NaOCl
E) NaNO₃

Question 57

The pH of a 0.50 M solution of the weak monoprotic acid HA is 4.76. The value of K_a is

A) 6.0 × 10^-10
B) 1.7 × 10^-5
C) 3.5 × 10^-5
D) 7.6 × 10^-4
E) 9.24

Question 58

Which statement is not correct?

A) a Lewis acid is a substance that can accept a pair of electrons to form a new bond
B) a Lewis base is a substance that can donate a pair of electrons to form a new bond
C) Al(OH)₃ is an amphoteric substance that can form either a positive or negative ion
D) Neutral molecules cannot act as Lewis acids
E) Ag(NH₃)₂⁺ is a complex ion, formed from a Ag⁺ ion (Lewis acid) and two NH₃ molecules (Lewis bases)

Question 59

The pH of a 0.172 M solution of benzoic acid (K_a = 6.31 × 10^-5) is

A) 2.48.
B) 3.44.
C) 4.37.
D) 4.96.
E) 5.63.

Question 60

Identify which of the hydrohalic acids is unlike the others, and why.

A) HF(aq), because it is the only strong acid
B) HCl(aq), because it is the only weak acid
C) HBr(aq), because it is a liquid at room temperature
D) HI(aq), because it does not display hydrogen bonding
E) HF(aq), because it displays hydrogen bonding

Question 61

Answer the following questions:

A) Write the reaction for the ionization of the weak acid HA in water.
B) Write the reaction for the hydrolysis of the conjugate base of the weak acid HA in water.
C) Using equilibrium constant expressions for the reaction of HA and of its conjugate base A- with water, prove that the product of Ka for a weak acid and Kb for its conjugate base equals 1.0 ´ 10-14 at 25°C.

Question 62

A solution of acetic acid (K_a = 1.8 × 10^-5) has a pH exactly 2 higher than a solution of HCl(aq) of the same concentration. What is that concentration?