Question 1

The substance NH3 is considered

Accepted Answer

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

Question 2

What is the pH of a 0.0035 M KOH solution?

Accepted Answer

A)  2.46 
B)  5.65 
C)  8.35 
D)  11.54 
E)  none of the above 
A)  2.46 
B)  5.65 
C)  8.35 
D)  11.54 
E)  none of the above

Question 3

In order to be a Brønsted-Lowry base, a species must contain a proton.

Accepted Answer

A) True 
 B)False

Question 4

Define an acid according to the Lewis theory. Write a balanced equation in support of this definition, in which the acid is neither an Arrhenius acid nor a Brønsted-Lowry acid.

Accepted Answer

According to Lewis, an acid is

Question 5

Select the correct relationship among the concentrations of species present in a 1.0 M aqueous solution of the weak acid represented by HA.

Accepted Answer

A)  [H2O] > [A-] ~ [H3O+] > [HA] > [OH-] 
B)  [H2O] > [HA] > [A-] > [H3O+] > [OH-] 
C)  [HA] > [H2O] > [A-] > [H3O+] > [OH-] 
D)  [H2O] > [HA] > [A-] ~ [H3O+] > [OH-] 
E)  [HA] > [H2O] > [A-] ~ [H3O+] > [OH-] 
A)  [H2O] > [A-] ~ [H3O+] > [HA] > [OH-] 
B)  [H2O] > [HA] > [A-] > [H3O+] > [OH-] 
C)  [HA] > [H2O] > [A-] > [H3O+] > [OH-] 
D)  [H2O] > [HA] > [A-] ~ [H3O+] > [OH-] 
E)  [HA] > [H2O] > [A-] ~ [H3O+] > [OH-]

Question 6

Which of the following aqueous systems has the highest pH?

Accepted Answer

A)  0.1 M HA, pKa = 11.89 
B)  0.1 M HMO, pKa = 8.23 
C)  0.1 M HA, pKa = 4.55 
D)  0.1 M HBO, pKa = 2.43 
E)  pure water 
A)  0.1 M HA, pKa = 11.89 
B)  0.1 M HMO, pKa = 8.23 
C)  0.1 M HA, pKa = 4.55 
D)  0.1 M HBO, pKa = 2.43 
E)  pure water

Question 7

All Lewis acids contain at least one proton.

Accepted Answer

A) True 
 B)False

Question 8

Farmers who raise cotton once used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 × 10-4, K2 = 5.6 × 10-8, and K3 = 3 × 10-13. What is the pH of a 0.500 M solution of arsenic acid?

Accepted Answer

A)  0.85 
B)  1.96 
C)  3.90 
D)  4.51 
E)  none of the above 
A)  0.85 
B)  1.96 
C)  3.90 
D)  4.51 
E)  none of the above

Question 9

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

Accepted Answer

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

Question 10

Phosphoric acid, H3PO4, is a triprotic acid, for which Ka1 = 7.2 × 10-3, Ka2 = 6.3 × 10-8 and Ka3 = 4.2 × 10-13. What is the value of Kb for the hydrogen phosphate anion, HPO42-?

Accepted Answer

A)  6.3 × 10-8 
B)  4.2 × 10-13 
C)  1.4 × 10-12 
D)  1.6 × 10-7 
E)  2.4 × 10-2 
A)  6.3 × 10-8 
B)  4.2 × 10-13 
C)  1.4 × 10-12 
D)  1.6 × 10-7 
E)  2.4 × 10-2

Question 11

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 Ka for the acid?

Accepted Answer

A)  0.36 
B)  2.4 × 10-2 
C)  7.8 × 10-3 
D)  1.5 × 10-5 
E)  none of the above 
A)  0.36 
B)  2.4 × 10-2 
C)  7.8 × 10-3 
D)  1.5 × 10-5 
E)  none of the above

Question 12

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?

Accepted Answer

A)  0.022 M 
B)  0.052 M 
C)  0.15 M 
D)  0.29 M 
E)  none of the above 
A)  0.022 M 
B)  0.052 M 
C)  0.15 M 
D)  0.29 M 
E)  none of the above

Question 13

What is the pH of a 0.050 M LiOH solution?

Accepted Answer

A)  < 1.0 
B)  1.30 
C)  3.00 
D)  11.00 
E)  12.70 
A)  < 1.0 
B)  1.30 
C)  3.00 
D)  11.00 
E)  12.70

Question 14

Given: H2O(aq) + H2O(l)     H3O+(aq) + OH-(aq) F1F1F1S1F1F1F10H°rxn > 0
When the temperature of a sample of pure water is raised above 25 °C,

Accepted Answer

A)  the hydronium ion concentration will be greater than the hydroxide ion concentration. 
B)  the hydronium ion concentration will be less than the hydroxide ion concentration. 
C)  the value of Kw will increase. 
D)  the hydronium ion concentration could change to 1.0 × 10-10 M. 
E)  the hydroxide ion concentration could change to 1.0 × 10-10 M. 
A)  the hydronium ion concentration will be greater than the hydroxide ion concentration. 
B)  the hydronium ion concentration will be less than the hydroxide ion concentration. 
C)  the value of Kw will increase. 
D)  the hydronium ion concentration could change to 1.0 × 10-10 M. 
E)  the hydroxide ion concentration could change to 1.0 × 10-10 M.

Question 15

What is the pH of a 0.20 M HCl solution?

Accepted Answer

A)  < 0 
B)  0.70 
C)  1.61 
D)  12.39 
E)  13.30 
A)  < 0 
B)  0.70 
C)  1.61 
D)  12.39 
E)  13.30

Question 16

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

Accepted Answer

A)  0.64 
B)  0.94 
C)  1.13 
D)  2.16 
E)  none of the above 
A)  0.64 
B)  0.94 
C)  1.13 
D)  2.16 
E)  none of the above

Question 17

The chloride ion, Cl-, is a typical Lewis acid.

Accepted Answer

A) True 
 B)False

Question 18

What is the value of Kb for the cyanide anion, CN-? Ka(HCN) = 6.2 × 10-10

Accepted Answer

A)  1.6 × 10-4 
B)  1.6 × 10-5 
C)  3.8 × 10-4 
D)  3.8 × 10-5 
E)  6.2 × 104 
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 19

Select the pair of substances in which an acid is listed followed by its conjugate base.

Accepted Answer

A)  H+, HCl 
B)  NH3, NH4+ 
C)  HPO42-, H2PO4- 
D)  HCO3-, CO32- 
E)  CH3COOH, CH3COOH2+ 
A)  H+, HCl 
B)  NH3, NH4+ 
C)  HPO42-, H2PO4- 
D)  HCO3-, CO32- 
E)  CH3COOH, CH3COOH2+

Question 20

Select the pair of substances which is not a conjugate acid-base pair.

Accepted Answer

A)  H3O+, H2O 
B)  HNO2, NO2- 
C)  H2SO4, HSO4- 
D)  H2S, S2- 
E)  NH3, NH2- 
A)  H3O+, H2O 
B)  HNO2, NO2- 
C)  H2SO4, HSO4- 
D)  H2S, S2- 
E)  NH3, NH2-

Exam 18: Acid-Base Equilibria

The substance NH3 is considered

What is the pH of a 0.0035 M KOH solution?

In order to be a Brønsted-Lowry base, a species must contain a proton.

Define an acid according to the Lewis theory. Write a balanced equation in support of this definition, in which the acid is neither an Arrhenius acid nor a Brønsted-Lowry acid.

Select the correct relationship among the concentrations of species present in a 1.0 M aqueous solution of the weak acid represented by HA.

Which of the following aqueous systems has the highest pH?

All Lewis acids contain at least one proton.

Farmers who raise cotton once used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 × 10-4, K2 = 5.6 × 10-8, and K3 = 3 × 10-13. What is the pH of a 0.500 M solution of arsenic acid?

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

Phosphoric acid, H3PO4, is a triprotic acid, for which Ka1 = 7.2 × 10-3, Ka2 = 6.3 × 10-8 and Ka3 = 4.2 × 10-13. What is the value of Kb for the hydrogen phosphate anion, HPO42-?

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 Ka for the acid?

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?

What is the pH of a 0.050 M LiOH solution?

Given: H2O(aq) + H2O(l) H3O+(aq) + OH-(aq) H°rxn > 0 When the temperature of a sample of pure water is raised above 25 °C,

What is the pH of a 0.20 M HCl solution?

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

The chloride ion, Cl-, is a typical Lewis acid.

What is the value of Kb for the cyanide anion, CN-? Ka(HCN) = 6.2 × 10-10

Select the pair of substances in which an acid is listed followed by its conjugate base.

Select the pair of substances which is not a conjugate acid-base pair.

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

The Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main Group Elements: Bonding, Structure, and Reactivity

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

The substance NH₃is considered

Farmers who raise cotton once used arsenic acid, H₃AsO₄, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K₁= 2.5 × 10^-4, K₂= 5.6 × 10^-8, and K₃= 3 × 10^-13. What is the pH of a 0.500 M solution of arsenic acid?

Hydroxylamine, HONH₂, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has K_b of 9.1 × 10^-9. What is the pH of a 0.025 M HONH₂solution?

Phosphoric acid, H₃PO₄, is a triprotic acid, for which K_a1 = 7.2 × 10^-3, K_a2 = 6.3 × 10^-8 and K_a3= 4.2 × 10^-13. What is the value of K_b for the hydrogen phosphate anion, HPO₄^2-?

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?

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?

Given: H₂O(aq) + H₂O(l) H₃O⁺(aq) + OH^-(aq) H°_rxn > 0 When the temperature of a sample of pure water is raised above 25 °C,

The chloride ion, Cl^-, is a typical Lewis acid.

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