Question 1

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H3PO4 + H2O ⇌ H2PO4- + H3O+

Accepted Answer

A) acid 
B) base 
C) neither 
D) both 
E) none of the above

Question 2

Which of the half-reactions below would be complementary and balance the following half-reaction? Zn+2 → Zn

Accepted Answer

A) Cu → Cu+2 
B) K+ → K 
C) 2 Cu → 2 Cu+2 
D) 2 K+ → 2 K 
E) Cl2 → 2 Cl-

Question 3

Upon combustion, about how many grams of water vapor are produced from every 16 grams of methane, CH4? CH4 + 2 O2 → CO2 + 2 H2O

Accepted Answer

A) 16 grams 
B) 18 grams 
C) 36 grams 
D) 8 grams

Question 4

What element is behaves as the oxidizing agent in the following equation and what element behaves as the reducing agent? Sn2+ + 2 Ag → Sn + 2 Ag+

Accepted Answer

A) The tin ion, Sn2+, is the oxidizing agent while silver, Ag, is the reducing agent. 
B) The tin ion, Sn2+, is the reducing agent while silver, Ag, is the oxidizing agent. 
C) The tin, Sn, is the reducing agent while silver ion, Ag+, is the oxidizing agent. 
D) The tin, Sn, is the oxidizing agent while silver ion,Ag+, is the reducing agent.

Question 5

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn → Zn+2 + 2e- 
Rxn B: 2 NH4+ + 2e- → 2 NH3 + H2
Which reaction is taking place at the cathode?

Accepted Answer

A) rxn A 
B) rxn B 
C) Both reactions are happening at both the anode and cathode. 
D) Both reactions are happening are happening at the electrode. 
E) The reaction takes place at the electrode, not the cathode.

Question 6

In the oxidation-reduction reaction Mg(s)+ Cu2+ (aq)→ 3 Mg2+ (aq)+ Cu(s), which atom or ion is reduced? Which atom or ion is oxidized?

Accepted Answer

A) The Cu2+ ion is oxidized as it gains electrons from the copper metal, Cu. The magnesium metal, Mg, is reduced as it loses electrons to form Mg2+. 
B) The Mg2+ ion is reduced as it gains electrons from the copper metal, Cu. The Cu2+ is oxidized as it loses electrons to the Mg2+. 
C) The Cu2+ ion is reduced as it gains electrons to form copper metal, Cu. The magnesium metal, Mg, is oxidized as it loses electrons to form Mg2+. 
D) Since Mg goes from a solid to an aqueous solution and Cu goes from an aqueous solution to a solid, an oxidation-reduction reaction did not occur.

Question 7

For the following acid-base reaction, identify what is formed in the space marked. H2SO4 + KOH ⇌ KHSO4 + ???

Accepted Answer

A) K2SO4 
B) H3OSO4 
C) H2O 
D) KOH2SO4 
E) none of the above

Question 8

In the above diagram, which atom behaves as the oxidizing agent, the lighter colored atom or the darker colored atom?

Accepted Answer

A) Both atoms behave as the oxidizing agent. 
B) Neither of the atoms behave as the oxidizing agent. 
C) The darker colored atom behaves as the oxidizing agent. 
D) The lighter colored atom behaves as the oxidizing agent.

Question 9

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? ____ Sn2+ + ____ Ag → ____ Sn + ____ Ag+

Accepted Answer

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

Question 10

What happens to the pH of an acidic solution as water is added?

Accepted Answer

A) The pH is not influenced by the addition of water. 
B) The pH will decrease as the solution becomes more dilute. 
C) The pH will increase as the solution becomes more dilute. 
D) The pH will decrease since more hydronium ions are produced from the water.

Question 11

Hydrogen sulfide, H2S, burns in the presence of oxygen, O2, to produce water, H2O, and sulfur dioxide, SO2. Through this reaction, is sulfur oxidized or reduced? 2 H2S + 3 O2 → 2 H2O + 2 SO2

Accepted Answer

A) Sulfur is reduced. 
B) Sulfur is oxidized 
C) Sulfur is both oxidized and reduced. 
D) Sulfur is neither oxidized nor reduced.

Question 12

Why might disposing of a lead-acid battery, nickel-cadmium battery or mercury battery in a landfill be a bad thing?

Accepted Answer

A) Cadmium, mercury, and lead are all toxic metals and could leak out of the landfill. 
B) Cadmium, mercury, and lead are all very reactive and generate highly unstable compounds. 
C) Cadmium, mercury, and lead are all radioactive and release radiation. 
D) all of the above 
E) none of the above

Question 13

What does the value of Kw say about the extent to which water molecule react with themselves?

Accepted Answer

A) Because the value of Kw is so small, the extent to which water ionizes is quite large. 
B) Because the value of Kw is so small, the extent to which water ionizes is quite small. 
C) Water molecules react with themselves at a constant rate, never increasing or decreasing. 
D) When an acid is added to water, the value of Kw will decrease.

Question 14

Rust has a tendency to form when iron in contact with water reacts according to the following reaction: 4 Fe + 3 O2 → 2 Fe2O3
What is happening at the anodic region?

Accepted Answer

A) Iron is being oxidized. 
B) Oxygen is being oxidized. 
C) Oxygen is being reduced. 
D) Iron is being reduced. 
E) none of the above

Question 15

As the pH increases, the hydroxide ion concentration ________.

Accepted Answer

A) goes down 
B) gets larger 
C) starts to affect the H+ concentration 
D) starts to decrease because it is reacting with the excess hydronium ions 
E) stays constant

Question 16

When the hydronium ion concentration equals 10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Accepted Answer

A) pH = 0, this is an acidic solution. 
B) pH = 1, this is an acidic solution. 
C) pH = -1, this is an acidic solution. 
D) pH = 7, this is a neutral solution.

Question 17

Which of the following statements is not true about a neutralization reaction?

Accepted Answer

A) Water is always formed in a neutralization reaction. 
B) One molecule of acid neutralizes one molecule of base. 
C) A neutralization is the reaction of a hydroxide ion with a proton. 
D) All of the above are true. 
E) None of the above are true.

Question 18

If the pH of a solution is 10, what is the hydroxide ion concentration?

Accepted Answer

A) 1 × 10-4 M 
B) 4 M 
C) 14 M 
D) -14 M 
E) -1 × 1014 M

Question 19

Which of the half-reactions below would be complementary, balance the following half-reaction, and be chemically reasonable? Br2 → 2 Br-

Accepted Answer

A) 2 K → 2 K+ 
B) K+ → K 
C) K → K+ 
D) 2 K+ → 2 K 
E) K → K+2

Question 20

Iron atoms have a greater tendency to oxidize than do copper atoms. Is this good news or bad news for a home in which much of the plumbing consists of iron and copper pipes connected together? Explain.

Accepted Answer

A) This is bad news, since the iron atoms will be reduced by the copper atoms. 
B) This is not a problem, since the strength of the copper will make up for the weakness of the iron. 
C) It is bad news. The iron atoms will lose electrons to the copper atoms, which will pass those electrons onto oxygen atoms that are in contact with the surface. 
D) This is not a problem since any electrons lost will be replaced by copper electrons.

Exam 18: Two Classes of Chemical Reactions

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H₃PO₄ + H₂O ⇌ H₂PO₄^- + H₃O⁺

Which of the half-reactions below would be complementary and balance the following half-reaction? Zn⁺² → Zn

Upon combustion, about how many grams of water vapor are produced from every 16 grams of methane, CH₄? CH₄ + 2 O₂ → CO₂ + 2 H₂O

What element is behaves as the oxidizing agent in the following equation and what element behaves as the reducing agent? Sn²⁺ + 2 Ag → Sn + 2 Ag⁺

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn → Zn⁺² + 2e^- Rxn B: 2 NH₄⁺ + 2e^- → 2 NH₃ + H₂ Which reaction is taking place at the cathode?

In the oxidation-reduction reaction Mg(s) + Cu²⁺ (aq) → 3 Mg²⁺ (aq) + Cu(s) , which atom or ion is reduced? Which atom or ion is oxidized?

For the following acid-base reaction, identify what is formed in the space marked. H₂SO₄ + KOH ⇌ KHSO₄ + ???

In the above diagram, which atom behaves as the oxidizing agent, the lighter colored atom or the darker colored atom?

What happens to the pH of an acidic solution as water is added?

Hydrogen sulfide, H₂S, burns in the presence of oxygen, O₂, to produce water, H₂O, and sulfur dioxide, SO₂. Through this reaction, is sulfur oxidized or reduced? 2 H₂S + 3 O₂ → 2 H₂O + 2 SO₂

Why might disposing of a lead-acid battery, nickel-cadmium battery or mercury battery in a landfill be a bad thing?

What does the value of K_w say about the extent to which water molecule react with themselves?

Rust has a tendency to form when iron in contact with water reacts according to the following reaction: 4 Fe + 3 O₂ → 2 Fe₂O₃ _{What is happening at the anodic region?}

As the pH increases, the hydroxide ion concentration ________.

When the hydronium ion concentration equals 10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Which of the following statements is not true about a neutralization reaction?

If the pH of a solution is 10, what is the hydroxide ion concentration?

Which of the half-reactions below would be complementary, balance the following half-reaction, and be chemically reasonable? Br₂ → 2 Br^-

Iron atoms have a greater tendency to oxidize than do copper atoms. Is this good news or bad news for a home in which much of the plumbing consists of iron and copper pipes connected together? Explain.

Exam 18: Two Classes of Chemical Reactions

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H3PO4 + H2O ⇌ H2PO4- + H3O+

Which of the half-reactions below would be complementary and balance the following half-reaction? Zn+2 → Zn

Upon combustion, about how many grams of water vapor are produced from every 16 grams of methane, CH4? CH4 + 2 O2 → CO2 + 2 H2O

What element is behaves as the oxidizing agent in the following equation and what element behaves as the reducing agent? Sn2+ + 2 Ag → Sn + 2 Ag+

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn → Zn+2 + 2e- Rxn B: 2 NH4+ + 2e- → 2 NH3 + H2 Which reaction is taking place at the cathode?

In the oxidation-reduction reaction Mg(s) + Cu2+ (aq) → 3 Mg2+ (aq) + Cu(s) , which atom or ion is reduced? Which atom or ion is oxidized?

For the following acid-base reaction, identify what is formed in the space marked. H2SO4 + KOH ⇌ KHSO4 + ???

In the above diagram, which atom behaves as the oxidizing agent, the lighter colored atom or the darker colored atom?

What happens to the pH of an acidic solution as water is added?

Hydrogen sulfide, H2S, burns in the presence of oxygen, O2, to produce water, H2O, and sulfur dioxide, SO2. Through this reaction, is sulfur oxidized or reduced? 2 H2S + 3 O2 → 2 H2O + 2 SO2

Why might disposing of a lead-acid battery, nickel-cadmium battery or mercury battery in a landfill be a bad thing?

What does the value of Kw say about the extent to which water molecule react with themselves?

Rust has a tendency to form when iron in contact with water reacts according to the following reaction: 4 Fe + 3 O2 → 2 Fe2O3 What is happening at the anodic region?

As the pH increases, the hydroxide ion concentration ________.

When the hydronium ion concentration equals 10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Which of the following statements is not true about a neutralization reaction?

If the pH of a solution is 10, what is the hydroxide ion concentration?

Which of the half-reactions below would be complementary, balance the following half-reaction, and be chemically reasonable? Br2 → 2 Br-

Iron atoms have a greater tendency to oxidize than do copper atoms. Is this good news or bad news for a home in which much of the plumbing consists of iron and copper pipes connected together? Explain.

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H₃PO₄ + H₂O ⇌ H₂PO₄^- + H₃O⁺

Which of the half-reactions below would be complementary and balance the following half-reaction? Zn⁺² → Zn

Upon combustion, about how many grams of water vapor are produced from every 16 grams of methane, CH₄? CH₄ + 2 O₂ → CO₂ + 2 H₂O

What element is behaves as the oxidizing agent in the following equation and what element behaves as the reducing agent? Sn²⁺ + 2 Ag → Sn + 2 Ag⁺

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn → Zn⁺² + 2e^- Rxn B: 2 NH₄⁺ + 2e^- → 2 NH₃ + H₂ Which reaction is taking place at the cathode?

In the oxidation-reduction reaction Mg(s) + Cu²⁺ (aq) → 3 Mg²⁺ (aq) + Cu(s) , which atom or ion is reduced? Which atom or ion is oxidized?

For the following acid-base reaction, identify what is formed in the space marked. H₂SO₄ + KOH ⇌ KHSO₄ + ???

Hydrogen sulfide, H₂S, burns in the presence of oxygen, O₂, to produce water, H₂O, and sulfur dioxide, SO₂. Through this reaction, is sulfur oxidized or reduced? 2 H₂S + 3 O₂ → 2 H₂O + 2 SO₂

What does the value of K_w say about the extent to which water molecule react with themselves?

Rust has a tendency to form when iron in contact with water reacts according to the following reaction: 4 Fe + 3 O₂ → 2 Fe₂O₃ _{What is happening at the anodic region?}

Which of the half-reactions below would be complementary, balance the following half-reaction, and be chemically reasonable? Br₂ → 2 Br^-