Deck 8: Acids and Bases

Question 1

Which of the following is an example of a diprotic acid?

A)NH₂⁻
B)H₂SO₄
C)HCl
D)CH₄
E)NH₂⁻ and H₂SO₄ are correct.

Answer 1

H₂SO₄

Question 2

Which of the following correctly describes what is meant by the term neutralization?

A)the reaction between hydroxide (OH−) and water to form a base
B)the reaction between a proton (H+) and water to form a hydronium ion (H₃O+)
C)the reaction between an acid and a base to form a salt and water
D)the reaction between two molecules of water, one acting as an acid and the other acting as a base
E)the reaction between an oxidizing agent and a reducing agent

Answer 2

the reaction between an acid and a base to form a salt and water

Question 3

Which statement correctly describes conjugate acids and bases according to the Brønsted-Lowry theory?

A)A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton.
B)A conjugate base is the species formed when an acid accepts a proton; a conjugate acid is the species formed when a base donates a proton.
C)A conjugate acid is the species formed when an acid donates a proton; a conjugate base is the species formed when a base accepts a proton.
D)A conjugate acid is an acid that does not completely transfer a proton to water; a conjugate base is a base that does not completely accept a proton from water.
E)A conjugate acid is the solution formed when an acid is added to water; a conjugate base is the solution formed when a base is added to water.

Answer 3

A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton.

Question 4

Formic acid (HCO₂H) is a weak acid found in the venom of bees and ant stings.Which of the following is an accurate statement concerning an aqueous solution of formic acid? HCO₂H(aq) + H₂O(l) H₃O⁺(aq) + HCO₂−(aq) K_a = 1.8 × 10⁻⁴

A)The reaction between formic acid and water is slow, due to the low value for K_a.
B)A formic acid solution predominantly contains undissociated HCO₂H molecules.
C)A formic acid solution predominantly contains H₃O⁺ and HCO₂− _ions.
D)A formic acid solution contains a greater concentration of dissolved ions than it does neutral formic acid molecules.
E)A formic acid solution contains equal amounts of H₃O⁺ and HCO₂H.

Question 5

A sample of black coffee was measured to have [H₃O⁺] = 7.94 × 10⁻⁶.What is TRUE about this solution?

A)The solution is acidic.
B)The solution contains less hydronium ions than pure water itself.
C)The solution does not contain any OH⁻ions.
D)The solution has [OH⁻] = 7.94 × 10⁻⁶.
E)The pH of the solution is 7.94.

Question 6

Which statement concerning the relative strength of acids is FALSE?

A)Strong and weak acids differ in their extent of proton transfer to water.
B)Strong acids are good proton donors; weak acids are poor proton donors.
C)A strong acid completely transfers its protons to water; a weak acid only partially transfers its protons to water.
D)Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases.
E)A strong acid produces more hydronium ions in water than a weak acid of the same concentration.

Question 7

Consider two beakers, one containing 1.0 M HCl and the other containing 1.0 M CH₃COOH.Which solution would have the lowest pH?

A)1.0 M CH₃COOH because its solution contains a lower hydronium ion concentration than 1.0 M HCl
B)1.0 M HCl because its solution contains a higher hydronium ion concentration than 1.0 M CH₃COOH
C)1.0 M HCl because its solution contains a lower hydronium ion concentration than 1.0 M CH₃COOH
D)1.0 M CH₃COOH because its solution contains a higher hydronium ion concentration than 1.0 M HCl
E)Both solutions would have the same pH because they have the same concentration.

Question 8

Which of the following best represents the autoionization, or self-ionization, of water?

A)H₂O(l) → H+(aq) + OH-(aq)
B)2H₂O(l) 2H₂(aq) + O₂(aq)
C)2H₂O(l) H3O+(aq) + OH-(aq)
D)H₂O(l) → H₂(aq) + O₂^-(aq)
E)H+(aq) + OH-(aq) → H₂O(l)

Question 9

The species that remains after an acid donates a proton is called its conjugate base.What is the conjugate base of the hydronium ion, H₃O⁺?

A)OH^-
B)H₂O^-
C)H₂O
D)H₂O⁺
E)H₃O⁺ has no conjugate base.

Question 10

Butyric acid is a weak acid.Which reaction equation properly represents the dissociation of butyric acid in water?

A)CH₃CH₂CH₂COOH(aq) + H₂O(l) → CH₃CH₂CH₂COO- (aq) + H₃O+(aq)
B)CH₃CH₂CH₂COOH(aq) + H₂O(l) CH₃CH2CH₂COO-(aq) + H₃O+(aq)
C)CH₃CH₂CH₂COOH(aq) + H₂O(l) → CH₃CH₂CH₂COOH₂+(aq) + OH-(aq)
D)CH₃CH₂CH₂COOH(aq) + H₂O(l) CH₂CH₂CH₂COOH(aq) + H₃O+(aq)

Question 11

Consider the following generalized buffer solution equilibrium: BH⁺(aq) + H₂O(l) H₃O⁺(aq) + B(aq)
When a small amount of a strong base such as sodium hydroxide is added to the solution, which of the four species shown would experience an increase in concentration? (Hint: Use LeChatelier's principle.)

A)BH⁺
B)H₂O
C)H₃O⁺
D)B
E)None of the species would increase in concentration.

Question 12

A buffer solution contains acetic acid (HC₂H₃O₂) at a concentration of 0.225 M and sodium acetate (NaC₂H₃O₂) at a concentration of 0.164 M.The value of K_a for acetic acid is 1.75 × 10^-5.What is the pH of this buffer solution?

A)0.137
B)0.862
C)2.40
D)4.62
E)4.76

Question 13

A buffer solution contains carbonic acid (H₂CO₃) and sodium bicarbonate (NaHCO₃), each at a concentration of 0.100 M.The relevant equilibrium is shown below.What is the pH of this buffer solution? H₂CO₃(aq) + H₂O(l) H₃O⁺(aq) + HCO₃−(aq) K_a = 4.5 × 10⁻⁷

A)4.50
B)7.00
C)6.35
D)7.65
E)2.16

Question 14

A particular buffer solution consists of a weak acid and its conjugate base.How could this buffer solution be modified so as to increase its buffer capacity against added base?

A)Increase the concentration of the weak acid.
B)Increase the concentration of its conjugate base.
C)Use a strong base and its conjugate acid instead.
D)Use a strong acid and its conjugate base instead.
E)Make the concentrations of the weak acid and its conjugate base equal.

Question 15

For the reaction shown below, which of the following correctly represents a conjugate acid-base pair? HCO₂H(aq) + H₂O(l) H₃O⁺(aq) + HCO₂−(aq)

A)HCO₂H/H₃O⁺
B)HCO₂H/H₂O
C)H₂O/HCO₂-
D)H₃O⁺/HCO₂-
E)HCO₂H/HCO₂−

Question 16

Titration of 15.0 mL of an NaOH solution required 7.4 mL of a 0.25 M KNO₃ solution.What is the molarity of the NaOH solution?

A)0.25 M
B)0.017 M
C)0.12 M
D)0.44 M
E)0.0019 M

Question 17

HCl is a strong electrolyte.A bottle of HCl contains the label 0.015 M HCl(aq).Which statement concerning this HCl solution is FALSE?

A)The solution is acidic.
B)The pH of the solution is 1.5.
C)The hydronium ion concentration in this solution is 0.015 M.
D)The solution has a higher concentration of hydronium ions than hydroxide ions.
E)The solution contains dissolved H₃O⁺ and Cl⁻ ions only; no HCl molecules are present.

Question 18

What is the conjugate acid of NH₂⁻_?

A)NH²⁻
B)NH₃
C)NH₄⁺
D)NH₂⁺
E)NH₄⁻

Question 19

What is always a characteristic of a solution that contains a buffer?

A)The solution is neutral and has a pH of 7.
B)The solution contains a small amount of solute dissolved in a large volume of solvent.
C)The solution has been diluted by the addition of solvent.
D)The solution resists large changes in pH when small amounts of acids or bases are added.
E)The solution maintains a constant pH value; no amount of added acid or base can change the pH.

Question 20

What is the conjugate base of H₂SO₄?

A)SO₄2⁻
B)HSO₄−
C)H₂SO₃
D)SO₄−
E)H₂PO₄+

Question 21

If the hydronium ion concentration of an aqueous solution at 25°C is 5 × 10^-6 M, what is the hydroxide ion concentration?

A)2 × 10^-10 M
B)2 × 10^-9 M
C)2 × 10^-8 M
D)2 × 10⁷ M
E)2 × 10^{19 M}

Question 22

Morphine is used medicinally as a pain reliever.If an aqueous solution of morphine has [H₃O⁺] = 1.1 × 10^-10 M, what is the pH of this solution?

A)1.00
B)3.69
C)8.96
D)9.96
E)11

Question 23

Which one of the following correctly represents a conjugate acid-base pair?

A)H₂O, O^-
B)H₃O⁺, OH^-
C)H₂CO₃, CO₃^2-
D)HCl, Cl₂
E)H₂CO₃, HCO₃^-

Question 24

Titration of 25.0 mL of an HCl solution of unknown concentration requires 14.8 mL of 0.100 M NaOH.What is the molar concentration of the HCl solution? NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)

A)0.592 M
B)5.87 M
C)0.0592 M
D)0.0692 M
E)1.25 M

Question 25

A solution containing a buffer has an initial pH of 8.78.If a student adds 5 drops of NaCl(aq) to this solution, what would be a reasonable pH for the resulting solution?

A)5.22
B)7.00
C)8.64
D)8.78
E)8.89

Question 26

A buffer solution is prepared by placing twice the concentration of propanoic acid (C₂H₅COOH, K_a=1.34 ×10^-5) as the concentration of its conjugate base sodium propanoate into a flask.The pH of the resulting buffer solution is best described as which of the following?

A)less than 4.87
B)4.87
C)between 4.87 and 9.00
D)greater than 11.00
E)Undeterminable; the concentrations of the acid and conjugate base must be given.

Question 27

What is the pH of a 1.0 × 10⁻⁴ M solution of KOH?

A)4.00
B)6.00
C)7.00
D)10.00
E)14.00

Question 28

Sodium hydroxide (NaOH) can react with phosphoric acid (H₃PO₄) in a neutralization reaction.What is the reacting ratio of NaOH to H₃PO₄?

A)1:1
B)1:3
C)3:8
D)2:7
E)3:1

Question 29

What is the hydronium ion concentration of a solution with a pH of 6.0?

A)1 × 10⁶ M
B)1 × 10^-6 M
C)6 × 10¹ M
D)6 × 10^-1 M
E)6 × 10^-14 M

Question 30

For the reaction shown below, which of the following is a conjugate acid-base pair? C₅H₅N(aq) + H₂O(l) C₅H₅NH⁺(aq) + OH⁻(aq)

A)C₅H₅N, H₂O
B)C₅H₅N, C₅H₅NH⁺
C)C₅H₅NH⁺, OH⁻
D)H₂O, OH⁻
E)C₅H₅N, C₅H₅NH⁺ and H₂O, OH⁻

Question 31

What is the pH of a solution that has [H₃O⁺] = 6.0 × 10^-3 M?

A)1.7 × 10^-12
B)2.22
C)3.60
D)5.12
E)11.78

Question 32

A solution containing a buffer has an initial pH of 8.78.If a student adds 5 drops of HCl(aq) to this solution, what would be a reasonable pH for the resulting solution?

A)5.22
B)7.00
C)8.64
D)8.78
E)8.89

Question 33

An aqueous solution with a low pH is necessary for a certain industrial process.Which of the following solutions would have the lowest pH?

A)2.0 M NaOH
B)0.5 M HCl
C)1.0 M acetic acid
D)1.0 M HCl
E)All solutions would have the same pH.

Question 34

The reaction of an acid with a base produces a salt and another product.What is the identity of the other product?

A)hydronium ion
B)water
C)a buffer
D)a proton
E)hydroxide ion

Question 35

What is the hydronium ion concentration of pure water at 25°C?

A)7.0 × 10⁷ M
B)7.0 × 10^-7 M
C)1.0 × 10⁷ M
D)1.0 × 10^{-7 M}
E)1.0 × 10^{-14 M}

Question 36

Which one of the following is NOT a characteristic property of a base?

A)tastes bitter
B)feels slippery
C)increases [H⁺] in water
D)is corrosive
E)causes many metal ions to precipitate

Question 37

A solution containing a buffer has an initial pH of 8.78.If a student adds 5 drops of NaOH(aq) to this solution, what would be a reasonable pH for the resulting solution?

A)7.00
B)8.64
C)8.78
D)8.89
E)12.25

Question 38

A patient's urine sample gave a reading of 8.2.What is the value of [H₃O⁺] in this solution?

A)6.0 × 10^-9 M
B)0.91 M
C)1.6 × 10^-8 M
D)1.6 × 10⁸ M
E)2.7 × 10^-4 M

Question 39

What term is used to describe the amount of strong acid or strong base that can be added to a buffer solution without significantly changing its pH?

A)buffer threshold
B)Henderson-Hasselbalch strength
C)conjugate acid-base capacity
D)buffer capacity
E)acid dissociation constant

Question 40

Calculate the molar concentration of a sodium hydroxide solution if 60.00 mL of this solution were required to neutralize 30.00 mL of a 0.150 M hydrochloric acid solution.NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)

A)3.00 M
B)6.00 M
C)0.0750 M
D)0.150 M
E)2.25 M

Question 41

Which of the following compounds is NOT considered a polyprotic acid?

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

Question 42

Strong acids are completely dissociated when dissolved in water.

Question 43

What is the [OH⁻] of a solution that has a pH = 10.95?

A)1.03 M
B)1.1 × 10^-11 M
C)8.9 × 10^-4 M
D)3.05 M
E)7.4 × 10^-5 M

Question 44

The combination of a weak acid and a strong acid form a buffer solution.

Question 45

A hydronium ion is a protonated water molecule.

Question 46

All buffer solutions operate at a pH at or near 7.

Question 47

All Brønsted-Lowry acids contain at least one hydrogen atom.

Question 48

The concentration of a weak acid or base affects its degree of dissociation in water.

Question 49

A pH of 0 is considered neutral.

Question 50

All metal hydroxides are strong bases.

Question 51

The addition of an acid to water increases the [H₃O⁺] and decreases the pH.

Question 52

What is the pH of a 0.035 M HCl solution?

A)3.50
B)1.46
C)2.27
D)5.59
E)12.54

Question 53

The pH of a 12.0 M solution of HCl is -1.1.

Question 54

The main buffer system found in blood is the HCl/Cl^- system.

Question 55

According to Arrhenius' theory of acids and bases, acids increase the hydrogen ion concentration in water.

Question 56

The ion-product of water is affected by a change in temperature.

Question 57

A standard solution is a solution whose concentration is accurately known.

Question 58

Nitric acid is a strong acid and dissociates completely when dissolved in water.

Question 59

All Brønsted-Lowry bases contain hydroxide.