Question 1

A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq). Which of the following is the balanced chemical reaction for this electrolysis reaction?

Accepted Answer

A) NaCl (aq)+ H2O → NaOH (aq)+ Cl2 (g)+ H2 (g) 
B) 2 NaCl (aq)+ H2O → Na2O (aq)+ 2 HCl (aq) 
C) 2 NaCl (aq)+ 2 H2O → 2 Na (s)+ O2 (g)+ 2 H2 (g)+ Cl2 (g) 
D) 2 NaCl (aq)+ H2O → 2 NaH (aq)+ Cl2O- (aq)

Question 2

Identify the acid or base behavior of each substance in these reactions: HSO4- + H2O ⇌ OH- + H2S

Accepted Answer

A) HS O4- acts as an acid, H2O acts as a base, OH- acts as an acid, H2S O4 acts as a base. 
B) HS O4- acts as an base, H2O acts as a acid, OH- acts as an acid, H2S O4 acts as a base. 
C) HS O4- acts as an acid, H2O acts as a base, OH- acts as an base, H2S O4 acts as a acid. 
D) HS O4- acts as an base, H2O acts as a acid, OH- acts as an base, H2S O4 acts as a acid.

Question 3

What is a reduction?

Accepted Answer

A) the gain of electrons 
B) the reduction of the number of electrons 
C) the loss of an electron from the valence shell 
D) the reaction of oxygen with a reductant 
E) the formation of red compounds in the presence of an oxidant

Question 4

What would be the concentration of hydronium ions in a solution that had a pH = -3? Why would such a solution be impossible to prepare?

Accepted Answer

A) Concentration of H3O+ = 3 M. It is impossible because it is hard to measure such a small amount of hydronium ions accurately. 
B) Concentration of H3O+ = 30 M. It is impossible because pH can not be negative. 
C) Concentration of H3O+ = 1030 M. It is impossible because any container used to hold the acid would immediately corrode. 
D) Concentration of H3O+ = 103 M. It is impossible because only so much acid can dissolve in water before the solution becomes saturated.

Question 5

Your car lights were left on while you were shopping, and now your car battery is dead. Has the pH of the battery fluid increased or decreased?

Accepted Answer

A) The pH of the battery fluid has increased. 
B) The pH of the battery fluid has decreased. 
C) The pH of the battery fluid does not change. 
D) Since the lights were left on and the battery is dead, the pH of the battery fluid must be zero.

Question 6

What would the concentration of H3O+ be if the concentration of OH- was 1 × 10-1M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A) 1 × 10-3 
B) 1 × 10-2 
C) 1 × 10-4 
D) 1 × 1013 
E) none of the above

Question 7

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn
What is undergoing an oxidation as written?

Accepted Answer

A) Zn 
B) ZnO 
C) MnO2 
D) Mn2O3 
E) none of the above

Question 8

What best describes what happens when an acid such as HCl is mixed with water?

Accepted Answer

A) The proton chemically bonded to the chlorine is transferred to a water molecule and forms a chloride ion and a hydronium ion. 
B) A proton from the chlorine nucleus is ejected and captured by a water molecule to form a negatively charged HCl and a new hydronium ion. 
C) A hydroxide ion from the water is transferred to the HCl molecule to form a proton and hydronium ion. 
D) HCl is not an acid. 
E) none of the above

Question 9

Which of the following statements about strong and weak acids is not true?

Accepted Answer

A) A weak acid is as corrosive as a strong acid. 
B) A weak acid dissociates in water. 
C) A strong acid will react with a strong base. 
D) A weak acid will react with a strong base. 
E) All of the above are untrue.

Question 10

Which of the following solutions is the most acidic?

Accepted Answer

A) a solution with a pH = 14 
B) a solution with a pH = 10 
C) a solution with a pH = 7 
D) a solution with a pH = 4 
E) All of the solutions are basic.

Question 11

Which of the above illustrations shows a basic aqueous solution?

Accepted Answer

A) A 
B) B 
C) C 
D) All of the above are neutral solutions. 
E) none of the above

Question 12

Chemical equations need to be balanced not only in terms of the number of atoms, but also by the charge. In other words, just as there should be the same number of atoms before and after the arrow of an equation, there should be the same charge. What set of coefficients is necessary to balance the following chemical equation? ____ Ce4+ + ____ Cl+ → ____ Ce3+ + ____ Cl2

Accepted Answer

A) 1, 2, 1, 1 
B) 2, 2, 2, 1 
C) 1, 4, 1, 2 
D) 3, 4, 3, 2

Question 13

Which of the following statements best describes a cathode?

Accepted Answer

A) the negatively charged electrode of a battery or electrochemical apparatus 
B) the place where oxidation is taking place in a battery or electrochemical apparatus 
C) the place from which electrons are flowing away from 
D) all of the above 
E) none of the above

Question 14

What is the primary difference between a fuel cell and a battery?

Accepted Answer

A) Fuel cells do not run down because they can be refueled; batteries run down and need to be recharged. 
B) Batteries can be recharged, fuel cells cannot. 
C) Batteries supply electricity; fuel cells supply heat. 
D) Fuel cells oxidize to supply electricity, batteries reduce to supply electricity. 
E) Fuel cells do not use metals as oxidants and reductants, batteries have a static reservoir of oxidant and reductant.

Question 15

If you had a 1 M solution of a weak base what would be its pH?

Accepted Answer

A) 1 
B) 6 
C) 7 
D) 8 
E) 13

Question 16

Arrange the following images of an aqueous base solution in order of increasing base strength:

Accepted Answer

A) A, B, C 
B) B, C, A 
C) C, B, A 
D) A, C, B 
E) All are equally strong.

Question 17

Which of the following statements about electrochemistry is not true?

Accepted Answer

A) It is the study of how electrical energy and chemical reactions are related. 
B) It involves the use of a set of oxidation-reduction reactions to produce electrical current. 
C) It involves the use of electrical current to produce an oxidation-reduction reaction. 
D) It is the study of how electrons are transferred from one chemical compound to another. 
E) All of the above are true.

Question 18

Which of the following solutions is the most acidic?

Accepted Answer

A) a solution with a pH = 14 
B) a solution with a pH = 12 
C) a solution with a pH = 7 
D) a solution with a pH = 13 
E) All of the solutions are basic.

Question 19

What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-8M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A) 1 × 10-14 
B) 1 × 10-6 
C) 1 × 108 
D) 1 × 106 
E) 1 × 10-8

Question 20

Why don't the electrodes of a fuel cell deteriorate the way the electrodes of a battery do?

Accepted Answer

A) As long as fuel is supplied, fuel cells don't run down, but car batteries die when the electron-producing chemicals are consumed. 
B) Fuel cell electrodes are made of graphite, which does not deteriorate. 
C) Fuel cell electrodes are self-replenishing thanks to the KOH-containing paste. 
D) Fuel cell do not use electrodes, so there are none to deteriorate.

Exam 18: Two Classes of Chemical Reactions

A major source of chlorine gas, Cl₂, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq) . Which of the following is the balanced chemical reaction for this electrolysis reaction?

Identify the acid or base behavior of each substance in these reactions: HSO₄^- + H₂O ⇌ OH^- + H₂S

What is a reduction?

What would be the concentration of hydronium ions in a solution that had a pH = -3? Why would such a solution be impossible to prepare?

Your car lights were left on while you were shopping, and now your car battery is dead. Has the pH of the battery fluid increased or decreased?

What would the concentration of H₃O⁺ be if the concentration of OH^- was 1 × 10^-1M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

In a battery, the following oxidation-reduction reactions are taking place: Mn₂O₃ + ZnO → 2 MnO₂ + Zn What is undergoing an oxidation as written?

What best describes what happens when an acid such as HCl is mixed with water?

Which of the following statements about strong and weak acids is not true?

Which of the following solutions is the most acidic?

Which of the above illustrations shows a basic aqueous solution?

Which of the following statements best describes a cathode?

What is the primary difference between a fuel cell and a battery?

If you had a 1 M solution of a weak base what would be its pH?

Arrange the following images of an aqueous base solution in order of increasing base strength:

Which of the following statements about electrochemistry is not true?

Which of the following solutions is the most acidic?

What would the concentration of OH^- be if the concentration of H₃O⁺ was 1 × 10^-8M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

Why don't the electrodes of a fuel cell deteriorate the way the electrodes of a battery do?

Exam 18: Two Classes of Chemical Reactions

A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq) . Which of the following is the balanced chemical reaction for this electrolysis reaction?

Identify the acid or base behavior of each substance in these reactions: HSO4- + H2O ⇌ OH- + H2S

What is a reduction?

What would be the concentration of hydronium ions in a solution that had a pH = -3? Why would such a solution be impossible to prepare?

Your car lights were left on while you were shopping, and now your car battery is dead. Has the pH of the battery fluid increased or decreased?

What would the concentration of H3O+ be if the concentration of OH- was 1 × 10-1M? [H3O+] × [OH-] = Kw = 1 × 10-14

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn What is undergoing an oxidation as written?

What best describes what happens when an acid such as HCl is mixed with water?

Which of the following statements about strong and weak acids is not true?

Which of the following solutions is the most acidic?

Which of the above illustrations shows a basic aqueous solution?

Which of the following statements best describes a cathode?

What is the primary difference between a fuel cell and a battery?

If you had a 1 M solution of a weak base what would be its pH?

Arrange the following images of an aqueous base solution in order of increasing base strength:

Which of the following statements about electrochemistry is not true?

Which of the following solutions is the most acidic?

What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-8M? [H3O+] × [OH-] = Kw = 1 × 10-14

Why don't the electrodes of a fuel cell deteriorate the way the electrodes of a battery do?

A major source of chlorine gas, Cl₂, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq) . Which of the following is the balanced chemical reaction for this electrolysis reaction?

Identify the acid or base behavior of each substance in these reactions: HSO₄^- + H₂O ⇌ OH^- + H₂S

What would the concentration of H₃O⁺ be if the concentration of OH^- was 1 × 10^-1M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

In a battery, the following oxidation-reduction reactions are taking place: Mn₂O₃ + ZnO → 2 MnO₂ + Zn What is undergoing an oxidation as written?

What would the concentration of OH^- be if the concentration of H₃O⁺ was 1 × 10^-8M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14