Deck 9: Acids and Bases

Question 1

Which of the following equations best describes what will happen to formic acid when it reacts with water?

A)
B)
C)
D)
E)

Answer 1

Question 2

Which of the following reactions illustrate the reaction of a base? I. NH₃ + H₂O → ⁺NH₄ + ^-OH
II) HCl + H₂O → H₃O⁺ + Cl^-
III) NaOH → Na⁺ + ^-OH
IV) ⁺NH₄ + H₂O → H₃O⁺ + NH₃

A) I only
B) II only
C) I and III
D) I, III, and IV
E) All of the above are reactions of a base.

Answer 2

All of the above are reactions of a base.

Question 3

Ethylene glycol and propylene glycol are both

A) hydrocarbons.
B) carboxylic acids.
C) diols.
D) ethers.
E) toxic organic acids.

Answer 3

diols.

Question 4

Which of the following statements best describes what happens when an acid reacts with water? I. The acid donates a proton.
II. Water donates a proton.
III. Water acts as a base.
IV. Hydronium is formed.
V. Hydroxide is formed.

A) I only
B) II only
C) I, III, and V
D) I, III, and IV
E) II and V

Question 5

Which of the following atomic diagrams best represents H⁺?

A)a
B)b
C)c
D)d
E)e

Question 6

The boxed species in the following reaction is

A) hydroxide.
B) hydronium.
C) a proton.
D) the acid.
E) the base.

Question 7

Which of the following statements about acids is NOT true?

A) An example of an acid is HBr.
B) An acid increases the concentration of hydroxide in solution.
C) An acid increases the concentration of protons in solution.
D) An acid increases the concentration of hydronium in solution.
E) An acid is a proton donor.

Question 8

Which of the following reactions best illustrates the reaction of an acid in aqueous solution?

A)
B)
C)
D)
E)

Question 9

Which of the following statements about bases is NOT true?

A) A base decreases the concentration of hydronium in solution.
B) An example of a base is Ca(OH)₂.
C) A base increases the concentration of hydroxide in solution.
D) A base is a proton acceptor.
E) A base is always negatively charged.

Question 10

Which of the following types of molecules and ions is NOT a base?

A) an anion
B) a cation
C) a neutral molecule containing a nonbonding pair of electrons
D) a tertiary nitrogen
E) All of these are bases.

Question 11

Which of the following molecules is a base?

A)
B)
C)
D)
E)

Question 12

Not all protons in a molecule can be donated in an acid-base reaction. Below are three molecules, each with the proton donated in an acid-base reaction circled. What do these protons have in common?

A) They are all attached to oxygen.
B) They are all in a carbon-containing molecule.
C) They are all attached to the most electronegative atom in the molecule.
D) They are the only hydrogens in the molecule.
E) They are all attached to carbon.

Question 13

Which of the following compounds is a Brønsted Lowry base, but not an Arrhenius base?

A) HCl
B) NaOH
C) NH₃
D) Ca(OH)₂
E) CH₃COOH

Question 14

The boxed species in the following reaction is

A) hydroxide.
B) hydronium.
C) a proton.
D) the acid.
E) the base.

Question 15

All acid-base reactions that we consider in this chapter occur in

A) acidic solution.
B) basic solution.
C) neutral solution.
D) water.
E) nonpolar solvents.

Question 16

Select the choice that correctly states whether the substance is an acid or a base.

A) Vinegar is basic.
B) Amines are basic.
C) Gastric juice is basic.
D) Sodium hydroxide is acidic.
E) Morphine is acidic.

Question 17

In the body, ethylene glycol (antifreeze) is metabolized to a(n)

A) hydrocarbon.
B) diol.
C) ether.
D) toxic organic acid.
E) Ethylene glycol is not metabolized.

Question 18

What do all bases have in common?

A) They contain an ^-OH group.
B) They contain a nitrogen.
C) They contain an oxygen.
D) They are salts.
E) They contain a nonbonding pair of electrons.

Question 19

According to the Arrhenius definition, which of the following compounds is a base?

A) I and III only
B) I, II and IV
C) All of these compounds
D) III only
E) IV only

Question 20

A hydrogen atom without an electron is referred to as

A) hydroxide.
B) hydronium.
C) a proton.
D) an acid.
E) a conjugate base.

Question 21

The boxed species in the following reaction is

A) hydroxide.
B) hydronium.
C) a proton.
D) the acid.
E) the conjugate base.

Question 22

Each circle is a sample of an aqueous acidic or basic solution. Which of the solutions contains a weak acid?

A)
B)
C)
D)
E)

Question 23

When a base is dissolved in water, it reacts to give _________ and ________.

A) hydroxide; hydronium
B) hydronium; the conjugate acid
C) hydroxide; the conjugate acid
D) hydronium; the conjugate base
E) hydroxide; the conjugate base

Question 24

Each circle is a sample of an aqueous acidic or basic solution. Which of the solutions contains a weak base?

A)
B)
C)
D)
E)

Question 25

When an acid is dissolved in water, it reacts to give _________ and ________.

A) hydroxide; hydronium
B) hydronium; the conjugate acid
C) hydroxide; the conjugate acid
D) hydronium; the conjugate base
E) hydroxide; the conjugate base

Question 26

Which of the following are conjugate acid-base pairs in the acid-base reaction between dopamine and water? I. H₂O and II. H₂O and ^-OH III. and IV. and ^-OH

A) I only
B) I and IV
C) II only
D) II and IV
E) II and III

Question 27

Which of the following bases is a strong base?

A) LiOH
B)
C) NH₂CH₂COOH
D) NH₂CH₂CH₂CH₂NH₂
E) All of the above molecules are strong bases.

Question 28

The boxed species in the following reaction is

A) hydroxide.
B) hydronium.
C) a proton.
D) the acid.
E) the base.

Question 29

Which of the following strong acids is found in the body?

A) HNO₃
B) HCl
C) H?₂SO₄
D) HClO₄
E) HBr

Question 30

How do strong and weak acids differ?

A) Strong acids dissociate completely in aqueous solution and weak acids don't.
B) Only strong acids produce hydronium in aqueous solution.
C) Strong acids donate protons and weak acids do not.
D) Strong acids increase the concentration of ^-OH in solution.
E) Weak acids degrade less readily than strong acids.

Question 31

Each circle is a sample of an aqueous acidic or basic solution. Which of the solutions contains a strong base?

A)
B)
C)
D)
E)

Question 32

Which of the following molecules is amphoteric?

A) CH₃NH₂
B) CH₃OH
C) CH₃COOH
D) H₂SO₄
E) NaOH

Question 33

Water can react as both an acid and a base, depending on its environment. Because of this characteristic, water is a(n) _________ molecule.

A) amphoteric
B) autonomous
C) complex
D) reactive
E) conjugated

Question 34

The following is the reaction of benzoic acid in water. Which of the following choices is a conjugate acid-base pair in this reaction?

A) benzoic acid and water
B) benzoate and hydronium
C) benzoic acid and hydronium
D) benzoic acid and benzoate
E) benzoate and water

Question 35

Which of the statements describes the following reaction? Mg(OH)₂ → Mg²⁺ + 2 HO ^-

A) This reaction is the dissociation of a strong acid.
B) This reaction is the dissociation of a weak acid.
C) This is the reaction of a strong base.
D) This is the reaction of a weak base.
E) This is not an acid-base reaction.

Question 36

Which of the following statements best describes the behavior of water in the acid-base reaction between dopamine and water?

A) Water is the acid.
B) Water is the base.
C) Water is the conjugate acid.
D) Water is the conjugate base.
E) Water is both an acid and a base.

Question 37

A conjugate acid-base pair is

A) the reactants in an acid-base reaction.
B) the products of an acid-base reaction.
C) two species that differ only by a proton.
D) two species that differ only by a hydroxyl group.
E) a single molecule that can act as both an acid and a base.

Question 38

Each circle is a sample of an aqueous acidic or basic solution. Which of the solutions contains a strong acid?

A)
B)
C)
D)
E)

Question 39

Generally, strong bases are hydroxide salts of

A) transition metals.
B) the halogens.
C) alkali and alkaline earth metals.
D) the noble gases.
E) any element.

Question 40

Which of the following acids is not a strong acid?

A) HCl
B) HI
C) HNO₃
D) CH₃COOH
E) H₂SO₄

Question 41

An alkene has a pK_a of 40, while an alkyne has a pK_a of 25. Which functional group is more acidic?

A) an alkyne, because it has a higher pK_a
B) an alkyne, because it has a lower pK_a
C) an alkene, because it has a higher pK_a
D) an alkene, because it has a lower pK_a
E) They have the same acidity.

Question 42

In the acid-base reaction between ammonia and water, which of the following statements best describes the concentration of ammonia and ammonium at equilibrium?

A) The concentration of ammonium is increasing.
B) There is no ammonium at equilibrium.
C) Their concentrations are equal.
D) Their concentrations are constant.
E) There is no ammonia at equilibrium.

Question 43

In the acid-base reaction between ammonia and water, which of the following substances are present at equilibrium?

A) Ammonia, water, ammonium, and hydroxide are all present at equilibrium.
B) Only ammonia and water are present at equilibrium.
C) Only ammonium and hydroxide are present at equilibrium.
D) Only hydroxide and hydronium are present at equilibrium.
E) It is not possible to say which molecules will be present at equilibrium.

Question 44

The pK_a of aspirin is 3.5. What is the K_a of aspirin?

A) 3.5
B) 1000
C) 0.54
D) 3.2 * 10^-4
E) 3.2 * 10³

Question 45

Arsenic poisoning is a serious problem in many parts of the world. When arsenic poisoning occurs, arsenic binds to proteins and eventually causes cellular damage. This leads to a variety of symptoms in humans including exhaustion, muscle weakness, organ failure, and cancer. Arsenic poisoning is commonly treated with a drug called dimercaprol (or BAL) that binds arsenic, which sets up a competing equilibrium within the body. Once arsenic reacts to form a complex with BAL, it can be excreted from the body. Arsenic-protein complex Arsenic + proteins + BAL Arsenic-BAL complex
How does treatment with BAL affect the equilibrium shown above?

A) Adding BAL does not affect the equilibrium.
B) Adding BAL pushes the reaction to the left.
C) Adding BAL pushes the reaction to the right.
D) Adding BAL causes less arsenic-BAL to be made.
E) Adding BAL causes more arsenic-protein complex to be made.

Question 46

Methylamide (CH₃CONH₂) has a K_a of 1 *10^-16. What is the pK_a of methylamide?

A) "-16"
B) '0"
C) "16"
D) "1 * 10^-16"
E) "-1 * 10^-16"

Question 47

Which substance is acting as the acid in the reverse reaction of the acid-base reaction below?

A) ammonia
B) water
C) ammonium
D) hydroxide
E) hydronium

Question 48

In the acid-base reaction between ammonia and water, which bond is made in order to make ammonia and water from ammonium and hydroxide?

A) H-H
B) N-O
C) N-H
D) O-H
E) All of the above

Question 49

A weak acid is also a _________ because it produces a low concentration of ions in solution.

A) weak electrolyte
B) strong electrolyte
C) nonelectrolyte
D) weak base
E) strong acid

Question 50

Which of the following is NOT a common use of a base?

A) Many fruits get their sour or tart taste from bases.
B) Amino acids contain bases.
C) Many pharmaceuticals are bases.
D) Cleaning agents are often bases.
E) Neurotransmitters are bases.

Question 51

Acetic acid (CH₃COOH) has a pK_a of 4.74, while ethanol (CH₃CH₂OH) has a pK_a of about 16. Which molecule is more acidic?

A) acetic acid, because it has a higher pK_a
B) acetic acid, because it has a lower pK_a
C) ethanol, because it has a higher pK_a
D) ethanol, because it has a lower pK_a
E) They have the same acidity.

Question 52

Which of the following statements best describes what it means for the acid-base reaction between acetic acid and water to be in equilibrium?

A) The mass of acetic acid and acetate is equal.
B) The number of moles of acetate equals the number of moles of acetic acid.
C) The number of moles of hydronium equals the number of moles of water.
D) The forward and reverse reactions proceed at the same rate.
E) The reaction is balanced.

Question 53

Which of the statements best describes the following reaction? HCOOH + H₂O HCOO 1^- + H₃O⁺

A) This reaction is the dissociation of a strong acid.
B) This reaction is the dissociation of a weak acid.
C) This is the reaction of a strong base.
D) This is the reaction of a weak base.
E) This is not an acid-base reaction.

Question 54

Which of the following acidic functional groups is often involved in biochemical reactions in the body?

A) HO ^-
B) H₂SO₄
C) RCOOH
D) H₃O⁺
E) ROR

Question 55

What does K_a measure?

A) the concentration of water at equilibrium
B) the concentration of products divided by reactants at equilibrium
C) the concentration of hydronium at equilibrium
D) the concentration of hydroxide at equilibrium
E) K_a is not a measurement

Question 56

The reaction between acetic acid and water is given below, followed by a list of changes that could be made to the reaction solution. Which of these changes will result in the equilibrium shifting to the left? Changes that could be made to the solution I. adding more CH₃COOH
II) removing H₂O
III) removing H₃O⁺
IV) adding more CH₃COO ^-

A) All of these changes will result in the equilibrium shifting to the left.
B) Only I will result in the equilibrium shifting to the left.
C) Only IV will result in the equilibrium shifting to the left.
D) I and III will result in the equilibrium shifting to the left.
E) II and IV will result in the equilibrium shifting to the left.

Question 57

In the acid-base reaction between ammonia and water, which bond is broken in order to give ammonium and hydroxide?

A) H-H
B) N-O
C) N-H
D) O-H
E) All of the above

Question 58

Which of the statements best describes the following reaction?

A) This reaction is the dissociation of a strong acid.
B) This reaction is the dissociation of a weak acid.
C) This is the reaction of a strong base.
D) This is the reaction of a weak base.
E) This is not an acid-base reaction.

Question 59

Ammonia and ammonium are both present in water at equilibrium, as shown by the following acid-base equation. What will happen if ammonium is added to a solution of ammonia and ammonium at equilibrium? NH₃ + H₂O ⁺NH₄ + ^-OH
Ammonia water ammonium hydroxide

A) Nothing.
B) The result is not predictable.
C) The ammonium will bubble.
D) The equilibrium will shift to the right.
E) The equilibrium will shift to the left.

Question 60

The following reaction is a reversible reaction. Which of the following statements best describes what it means for this reaction to be reversible?

A) This reaction only occurs in the reverse direction as written above.
B) All of the reactant molecules react to make product and then all of the product molecules react to make reactants again.
C) Forward and reverse reactions proceed at the same rate.
D) Forward and reverse reactions occur simultaneously.
E) The rate of the reverse reaction is must faster than the rate of the forward reaction.

Question 61

What is the pH of a solution with a [H₃O⁺] of 7.9 * 10 ^{- 11} M?

A) "10.1"
B) "-10.1"
C) "3.90"
D) "-3.90"
E) "11.9"

Question 62

Adding an acid to pure water will change which of the following values: [H₃O⁺], [HO ^- ], and/or K_w?

A) [H₃O⁺] only
B) [HO ^- ] only
C) K_w only
D) [H₃O⁺] and [HO ^- ], but not K_w
E) All of these values will be changed.

Question 63

The concentration of H₃O⁺ in a solution is 1 *10^-4 M. Which of the following statements describes how the concentration of ^-OH in the solution could be determined?

A) It is not possible to determine [^-OH].
B) Calculate pH
C) Measure the pH with a pH probe or dipstick
D) Solve for [-^--OH] using the ion-product constant equation
E) The [^-OH] is unchanged when an acid is added to a solution.

Question 64

What is the pH of a urine sample with a hydronium concentration of 7.9 * 10 ^{- 8}?

A) "-7.10"
B) "7.10"
C) "6.90"
D) "-6.90"
E) "7.00"

Question 65

Which of the following statements does NOT correctly describe pH?

A) pH is a measure of acidity of a solution.
B) pH is a measure of hydronium concentration in a solution.
C) The higher the pH, the more acidic a solution.
D) A pH of 7 is a neutral solution.
E) pH = -log [H₃O⁺].

Question 66

Which of the following solutions has the highest concentration of [ ^- OH]?

A) a solution with a [H₃O⁺] of 1 *10 ^{- 5} M
B) a solution with a [H₃O⁺] of 1 *10 ^{- 13} M
C) a solution with a [HO ^- ] of 1 *10^-5 M
D) a solution with a [HO^-] of 1 *10^-13 M
E) a solution with a [HO1^-] of 1 *10^-2 M

Question 67

What is the pH of a solution with a [H₃O⁺] of 1.0 *10 ^{- 5} M?

A) "9.00"
B) "1.0*10 ^{- 5} M"
C) "-5.00"
D) "-9.00"
E) "5.00"

Question 68

What is the concentration of H₃O⁺ and ^-OH in pure water at room temperature?

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

Question 69

Which statement does NOT correctly explain why it is so important for intracellular pH to be maintained between 7.35 and 7.45?

A) In this range, carboxylic acids, phosphate esters, and amines are ionized.
B) In this range, the molecules are trapped within the cell.
C) In this range, the concentration of biomolecules is high enough for key reactions to take place.
D) In this range, molecules in biochemical pathways can bind to enzymes appropriately.
E) In this range, molecules in biochemical pathways are inert.

Question 70

What is the [H₃O⁺] in a solution that has a [OH ^- ] of 3.2 *10 ^{- 4} M?

A) 3.2 * 10 ^{- 10} M
B) 3.2 *10¹⁰ M
C) 3.1 * 10F ^{- 11} M
D) 3.1 * 10¹¹ M
E) 1.0 *10 ^{- 7} M

Question 71

What is the pH of a solution with a [ ^- OH ] of 4.1 *10 ^{- 3} M?

A) "-2.39"
B) "2.39"
C) "11.6"
D) "-11.6"
E) "7.00"

Question 72

What is the pH of a solution with a [ ^- OH ] of 1.0 *10 ^{- 10} M?

A) "1.0 *10 ^{- 10}"
B) "10.0"
C) "4.00"
D) "-10.0"
E) "-4.00"

Question 73

Which of the following solutions has the highest concentration of [ ^- OH]?

A) a solution with a pH of 4
B) a solution with a pH of 10
C) a solution with a [H₃O⁺] of 6.8 *10 ^{- 5} M
D) a solution with a [H₃O⁺] of 1 *10 ^{- 13} M
E) a solution with a [HO ^- ] of 1 *10 ^{- 2} M

Question 74

What is the [OH ^- ] in a solution that has a [H₃O⁺] of 1 *10 ^{- 6} M?

A) 1 *10 ^{- 20} M
B) 1 *10 ^{- 8} M
C) 1 *10 ^{- 6} M
D) 1*10 ^{- 7} M
E) 1 * 10⁷ M

Question 75

At physiological pH, phosphate esters, such as the molecule of methyl phosphate shown below, are ionized. Which of the following choices is the ionized form of a phosphate ester?

A)
B)
C)
D)
E)

Question 76

A blood sample has a pH of 7.42. What is the concentration of hydronium in the sample?

A) "0.87 M"
B) "2.6 * 10⁷ M"
C) "-2.6* 10⁷ M"
D) "3.8 * 10⁸ M"
E) "3.8 *10 ^{- 8} M"

Question 77

The [H₃O⁺] of a solution with a pH of 2 is ______ the [H₃O⁺] of a solution with a pH of 3.

A) one-tenth
B) ten times
C) one-half
D) twice
E) the same as

Question 78

According to the following table, what is the most acidic fluid in the body?

A) gastric juice
B) sweat
C) urine
D) saliva
E) blood

Question 79

Which of the following pH ranges is referred to as physiological pH?

A) pH 6 - pH 8
B) pH 7.35 - pH 7.45
C) pH 6.7 - pH 6.8
D) pH 6.5 - pH 7.5
E) pH 5 - pH 8

Question 80

A sample of gastric juice has a pH of 1.20. What is the concentration of hydroxide in this sample?

A) 1.6 *10 ^{- 13} M
B) 6.3 *10 ^{- 2} M
C) 1.0 *10 ^{- 7} M
D) 6.3 *10¹² M
E) 6.3 *10 ^{- 16} M