Question 1

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

Accepted Answer

A)  11.69 
B)  8.68 
C)  5.32 
D)  2.31 
E)  < 2.0 
A)  11.69 
B)  8.68 
C)  5.32 
D)  2.31 
E)  < 2.0 A

Question 2

The substance Ba(OH)2 is considered

Accepted Answer

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

Question 3

The substance HClO4 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. C

Question 4

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

Accepted Answer

A)  > 10-5 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 
A)  > 10-5 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 5

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

Accepted Answer

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 
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 6

An aqueous solution is considered to be acidic if

Accepted Answer

A)  the hydroxide ion concentration is 10-6 M. 
B)  the hydrogen ion concentration is 10-8 M. 
C)  the hydroxide and hydrogen ion concentrations are equal. 
D)  the hydroxide ion concentration is greater than the hydrogen ion concentration. 
E)  the hydroxide ion concentration is 10-10 M. 
A)  the hydroxide ion concentration is 10-6 M. 
B)  the hydrogen ion concentration is 10-8 M. 
C)  the hydroxide and hydrogen ion concentrations are equal. 
D)  the hydroxide ion concentration is greater than the hydrogen ion concentration. 
E)  the hydroxide ion concentration is 10-10 M.

Question 7

Which, if any, of the following acids is strong?

Accepted Answer

A)  phosphoric 
B)  carbonic 
C)  acetic 
D)  water 
E)  none of the above 
A)  phosphoric 
B)  carbonic 
C)  acetic 
D)  water 
E)  none of the above

Question 8

The acid dissociation constant Ka 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)   SO42-(aq) + NH4+(aq)

Accepted Answer

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. 
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 9

Which one of the following substances will give an aqueous solution of pH closest to 7?

Accepted Answer

A)  KNO3 
B)  CO2 
C)  NH4I 
D)  NH3 
E)  CH3NH2 
A)  KNO3 
B)  CO2 
C)  NH4I 
D)  NH3 
E)  CH3NH2

Question 10

The substance NaNO3 is considered

Accepted Answer

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

Question 11

Which one of the following pairs is not a conjugate acid-base pair?

Accepted Answer

A)  H2O/OH- 
B)  H2O2/HO2- 
C)  OH-/O2- 
D)  H2PO4-/HPO42- 
E)  HCl/H+ 
A)  H2O/OH- 
B)  H2O2/HO2- 
C)  OH-/O2- 
D)  H2PO4-/HPO42- 
E)  HCl/H+

Question 12

(a) Write a balanced equation representing the reaction of the acid, H2PO4- with the base, water.
(b) Write the expression for Ka of H2PO4- in terms of concentrations of relevant species.

Accepted Answer

(a) H₂PO₄^-(aq

Question 13

Calcium oxide, CaO, also known as quick lime, will react with carbon dioxide to form calcium carbonate, CaCO3. Which species, if any, acts as a Lewis acid in the reaction?

Accepted Answer

A)  Ca2+ 
B)  O2- 
C)  CO2 
D)  CaCO3 
E)  None of the species acts as a Lewis acid in this reaction. 
A)  Ca2+ 
B)  O2- 
C)  CO2 
D)  CaCO3 
E)  None of the species acts as a Lewis acid in this reaction.

Question 14

What is the value of Ka for the methylammonium ion, CH3NH3+? Kb(CH3NH2) = 4.4 × 10-4

Accepted Answer

A)  4.4 × 10-4 
B)  4.8 × 10-6 
C)  4.4 × 10-10 
D)  2.3 × 10-11 
E)  4.4 × 10-18 
A)  4.4 × 10-4 
B)  4.8 × 10-6 
C)  4.4 × 10-10 
D)  2.3 × 10-11 
E)  4.4 × 10-18

Question 15

According to Brønsted and Lowry, which one of the following is not a conjugate acid-base pair?

Accepted Answer

A)  H3O+/OH- 
B)  CH3OH2+/CH3OH 
C)  HI/I- 
D)  HSO4-/SO42- 
E)  H2/H- 
A)  H3O+/OH- 
B)  CH3OH2+/CH3OH 
C)  HI/I- 
D)  HSO4-/SO42- 
E)  H2/H-

Question 16

Which one of the following will give a solution with a pH > 7, but is not an Arrhenius base in the strict sense?

Accepted Answer

A)  CH3NH2 
B)  NaOH 
C)  CO2 
D)  Ca(OH)2 
E)  CH4 
A)  CH3NH2 
B)  NaOH 
C)  CO2 
D)  Ca(OH)2 
E)  CH4

Question 17

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

Accepted Answer

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 
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 18

Arsenic acid, H3AsO4, is used industrially to manufacture insecticides. 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 concentration of the HAsO42- in a solution whose initial arsenic acid concentration was 0.35 M?

Accepted Answer

A)  9.4 × 10-3 M 
B)  2.5 × 10-4 M 
C)  8.8 × 10-5 M 
D)  5.6 × 10-8 M 
E)  none of the above 
A)  9.4 × 10-3 M 
B)  2.5 × 10-4 M 
C)  8.8 × 10-5 M 
D)  5.6 × 10-8 M 
E)  none of the above

Question 19

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

Accepted Answer

A)  7.2 × 101 
B)  0.16 
C)  0.099 
D)  0.0014 
E)  0.00027 
A)  7.2 × 101 
B)  0.16 
C)  0.099 
D)  0.0014 
E)  0.00027

Question 20

The substance H2SO3 is considered

Accepted Answer

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

Exam 18: Acid-Base Equilibria

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

The substance Ba(OH)2 is considered

The substance HClO4 is considered

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

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

An aqueous solution is considered to be acidic if

Which, if any, of the following acids is strong?

The acid dissociation constant Ka 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) SO42-(aq) + NH4+(aq)

Which one of the following substances will give an aqueous solution of pH closest to 7?

The substance NaNO3 is considered

Which one of the following pairs is not a conjugate acid-base pair?

(a) Write a balanced equation representing the reaction of the acid, H2PO4- with the base, water. (b) Write the expression for Ka of H2PO4- in terms of concentrations of relevant species.

Calcium oxide, CaO, also known as quick lime, will react with carbon dioxide to form calcium carbonate, CaCO3. Which species, if any, acts as a Lewis acid in the reaction?

What is the value of Ka for the methylammonium ion, CH3NH3+? Kb(CH3NH2) = 4.4 × 10-4

According to Brønsted and Lowry, which one of the following is not a conjugate acid-base pair?

Which one of the following will give a solution with a pH > 7, but is not an Arrhenius base in the strict sense?

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

Arsenic acid, H3AsO4, is used industrially to manufacture insecticides. 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 concentration of the HAsO42- in a solution whose initial arsenic acid concentration was 0.35 M?

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

The substance H2SO3 is considered

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

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

The substance Ba(OH)₂is considered

The substance HClO₄is considered

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

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

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

The substance NaNO₃is considered

(a) Write a balanced equation representing the reaction of the acid, H₂PO₄^- with the base, water. (b) Write the expression for K_a of H₂PO₄^- in terms of concentrations of relevant species.

Calcium oxide, CaO, also known as quick lime, will react with carbon dioxide to form calcium carbonate, CaCO₃. Which species, if any, acts as a Lewis acid in the reaction?

What is the value of K_a for the methylammonium ion, CH₃NH₃⁺? K_b(CH₃NH₂) = 4.4 × 10^-4

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

Arsenic acid, H₃AsO₄, is used industrially to manufacture insecticides. 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 concentration of the HAsO₄^2- in a solution whose initial arsenic acid concentration was 0.35 M?

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

The substance H₂SO₃is considered