Question 1

Why is the anode of a battery indicated with negative (-)sign?

Accepted Answer

A) Because that is where electrons are being generated. 
B) Because it is negative. 
C) Because it is positive. 
D) Because that is where electrons are being adsorbed. 
E) It is just a convention so the batteries are put in the MP3 player correctly. 
A) Because that is where electrons are being generated. 
B) Because it is negative. 
C) Because it is positive. 
D) Because that is where electrons are being adsorbed. 
E) It is just a convention so the batteries are put in the MP3 player correctly.

Question 2

How many electrons are gained or lost in the following half-reaction? Zn → Zn2+

Accepted Answer

A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained 
A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained

Question 3

The general chemical equation for photosynthesis is shown below. Through this reaction, are the oxygens in the water molecules, H2O, oxidized or reduced? 6   + 6   O →   + 6

Accepted Answer

A) The oxygens of the water molecules are oxidized. 
B) The oxygens of the water molecules are reduced. 
C) The oxygens of some of these water molecules are oxidized while others are reduced. 
D) The oxygens of the water molecules are neither oxidized nor reduced. 
A) The oxygens of the water molecules are oxidized. 
B) The oxygens of the water molecules are reduced. 
C) The oxygens of some of these water molecules are oxidized while others are reduced. 
D) The oxygens of the water molecules are neither oxidized nor reduced.

Question 4

How many electrons are gained or lost in the following half-reaction? C → C4-

Accepted Answer

A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained 
A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained

Question 5

Consider the following molecules. What is the relationship between the degree to which the molecule is oxidized and its polarity?

Accepted Answer

A) The greater the degree of oxidation, the more polar the molecule. Therefore, acetic acid is both the most oxidized and the most polar. 
B) The greater the degree of oxidation, the less polar the molecule. Therefore, ethane is both the most oxidized and the least polar. 
C) Only acetaldehyde and acetic acid are oxidized and polar because they contain a double-bonded carbon-oxygen bond, C=O. Of the two, acetaldehyde is more polar. 
D) There is no correlation between degree to which a molecule is oxidized and its polarity. 
A) The greater the degree of oxidation, the more polar the molecule. Therefore, acetic acid is both the most oxidized and the most polar. 
B) The greater the degree of oxidation, the less polar the molecule. Therefore, ethane is both the most oxidized and the least polar. 
C) Only acetaldehyde and acetic acid are oxidized and polar because they contain a double-bonded carbon-oxygen bond, C=O. Of the two, acetaldehyde is more polar. 
D) There is no correlation between degree to which a molecule is oxidized and its polarity.

Question 6

Which of the following elements would be most useful for creating a n-type silicon?

Accepted Answer

A) As 
B) Sn 
C) Pb 
D) B 
E) Ga 
A) As 
B) Sn 
C) Pb 
D) B 
E) Ga

Question 7

Metal ores are isolated from rock by taking advantage of differences in both physical and chemical properties. Cite examples given in the textbook where differences in physical properties are used.

Accepted Answer

A) the electrolysis of impure copper metal 
B) the addition of carbon to the iron ore blast furnace 
C) the addition of oil to a slurry of metal sulfides 
D) all of the above 
A) the electrolysis of impure copper metal 
B) the addition of carbon to the iron ore blast furnace 
C) the addition of oil to a slurry of metal sulfides 
D) all of the above

Question 8

What is the purpose of a salt-bridge?

Accepted Answer

A) to allow ions to migrate between solutions 
B) to allow people to cross over salt water 
C) to allow electrons to migrate through solutions 
D) to allow salt to form in the oxidation-reduction reactions 
E) none of the above 
A) to allow ions to migrate between solutions 
B) to allow people to cross over salt water 
C) to allow electrons to migrate through solutions 
D) to allow salt to form in the oxidation-reduction reactions 
E) none of the above

Question 9

What is a drawback of roasting metal sulfides?

Accepted Answer

A) Gases that produce acid rain are released. 
B) The process is very energy intensive. 
C) The metal obtained is often contaminated with carbon. 
D) all of the above 
E) only a and b 
A) Gases that produce acid rain are released. 
B) The process is very energy intensive. 
C) The metal obtained is often contaminated with carbon. 
D) all of the above 
E) only a and b

Question 10

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

Accepted Answer

A) Cu → Cu2+ 
B) K+ → K 
C) 2 Cu → 2 Cu2+ 
D) 2 K+ → 2 K 
E) Cl2 → 2 Cl- 
A) Cu → Cu2+ 
B) K+ → K 
C) 2 Cu → 2 Cu2+ 
D) 2 K+ → 2 K 
E) Cl2 → 2 Cl-

Question 11

Based on their relative positions in the periodic table, which might you expect to be a stronger oxidizing agent, chlorine or fluorine? Why?

Accepted Answer

A) Chlorine should behave as a stronger oxidizing agent because it has a smaller effective nuclear charge in its outermost shell. 
B) Fluorine should behave as a stronger oxidizing agent because it has a smaller effective nuclear charge in its outermost shell. 
C) Chlorine should behave as a stronger oxidizing agent because it has a greater effective nuclear charge in its outermost shell. 
D) Fluorine should behave as a stronger oxidizing agent because it has a greater effective nuclear charge in its outermost shell. 
A) Chlorine should behave as a stronger oxidizing agent because it has a smaller effective nuclear charge in its outermost shell. 
B) Fluorine should behave as a stronger oxidizing agent because it has a smaller effective nuclear charge in its outermost shell. 
C) Chlorine should behave as a stronger oxidizing agent because it has a greater effective nuclear charge in its outermost shell. 
D) Fluorine should behave as a stronger oxidizing agent because it has a greater effective nuclear charge in its outermost shell.

Question 12

The following set of redox reactions takes place between iron dipped in a solution of copper ions. Fe → Fe2+ + 2e-
Cu2+ + 2e- → Cu
Which of the following describes what is happening on the surface of the iron?

Accepted Answer

A) The copper starts to plate out on iron. 
B) The iron rusts in the water. 
C) The iron starts to plate out on the copper. 
D) The iron corrodes the copper. 
E) none of the above 
A) The copper starts to plate out on iron. 
B) The iron rusts in the water. 
C) The iron starts to plate out on the copper. 
D) The iron corrodes the copper. 
E) none of the above

Question 13

Why are combustion reactions generally exothermic?

Accepted Answer

A) Hydrogen easily pulls electrons from the oxygen in water molecules and are reduced. 
B) During combustion oxygen is oxidized, which gives off lots of energy. 
C) Combustion involves the transfer of electrons to oxygen, which has an extremely high tendency for gaining electrons. 
D) It is highly exothermic because combustion involves an oxidation-reduction reaction between a metallic material and oxygen. 
A) Hydrogen easily pulls electrons from the oxygen in water molecules and are reduced. 
B) During combustion oxygen is oxidized, which gives off lots of energy. 
C) Combustion involves the transfer of electrons to oxygen, which has an extremely high tendency for gaining electrons. 
D) It is highly exothermic because combustion involves an oxidation-reduction reaction between a metallic material and oxygen.

Question 14

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

Accepted Answer

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

Question 15

Which of the following describes an electrode?

Accepted Answer

A) Any material that conducts electrons into a media where electrochemical reactions are taking place. 
B) Any material that conducts electrons out of a media where electrochemical reactions are taking place. 
C) Any material that conducts electrons. 
D) Any material that is undergoing an oxidation-reduction reaction in a battery. 
E) either A or B 
A) Any material that conducts electrons into a media where electrochemical reactions are taking place. 
B) Any material that conducts electrons out of a media where electrochemical reactions are taking place. 
C) Any material that conducts electrons. 
D) Any material that is undergoing an oxidation-reduction reaction in a battery. 
E) either A or B

Question 16

Iron is useful for reducing copper ions to copper metal. Might it also be used to reduce sodium ions to sodium metal?

Accepted Answer

A) No, because sodium ions are too difficult to reduce. 
B) Yes, especially in that sodium has such a low ionization energy. 
C) No, because the sodium ions in turn oxidize the iron. 
D) Yes, especially in that sodium has such a high ionization energy. 
A) No, because sodium ions are too difficult to reduce. 
B) Yes, especially in that sodium has such a low ionization energy. 
C) No, because the sodium ions in turn oxidize the iron. 
D) Yes, especially in that sodium has such a high ionization energy.

Question 17

In one type of fuel cell, the following oxidation-reduction reactions are taking place: 2 H2 + O2 → 2 H2O
What is the oxidant?

Accepted Answer

A) H2 
B) O2 
C) H2O 
D) all of the above 
E) none of the above 
A) H2 
B) O2 
C) H2O 
D) all of the above 
E) none of the above

Question 18

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn
What is being formed at the cathode?

Accepted Answer

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

Question 19

How many electrons are transferred from iron atoms to oxygen atoms in the formation of two units of iron hydroxide, Fe   ?

Accepted Answer

A) 4 electrons 
B) 8 electrons 
C) 16 electrons 
D) 12 electrons 
A) 4 electrons 
B) 8 electrons 
C) 16 electrons 
D) 12 electrons

Question 20

How many electrons are gained or lost in the following half-reaction? Cl2 → 2 Cl-

Accepted Answer

A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained 
A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained

Why is the anode of a battery indicated with negative (-)sign?

How many electrons are gained or lost in the following half-reaction? Zn → Zn²⁺

The general chemical equation for photosynthesis is shown below. Through this reaction, are the oxygens in the water molecules, H₂O, oxidized or reduced? 6 + 6 O → + 6

How many electrons are gained or lost in the following half-reaction? C → C^4-

Consider the following molecules. What is the relationship between the degree to which the molecule is oxidized and its polarity?

Which of the following elements would be most useful for creating a n-type silicon?

Metal ores are isolated from rock by taking advantage of differences in both physical and chemical properties. Cite examples given in the textbook where differences in physical properties are used.

What is the purpose of a salt-bridge?

What is a drawback of roasting metal sulfides?

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

Based on their relative positions in the periodic table, which might you expect to be a stronger oxidizing agent, chlorine or fluorine? Why?

The following set of redox reactions takes place between iron dipped in a solution of copper ions. Fe → Fe²⁺ + 2e- Cu²⁺ + 2e- → Cu Which of the following describes what is happening on the surface of the iron?

Why are combustion reactions generally exothermic?

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

Which of the following describes an electrode?

Iron is useful for reducing copper ions to copper metal. Might it also be used to reduce sodium ions to sodium metal?

In one type of fuel cell, the following oxidation-reduction reactions are taking place: 2 H₂+ O₂ → 2 H₂O What is the oxidant?

In a battery, the following oxidation-reduction reactions are taking place: Mn₂O₃ + ZnO → 2 MnO₂ + Zn What is being formed at the cathode?

How many electrons are transferred from iron atoms to oxygen atoms in the formation of two units of iron hydroxide, Fe ?

How many electrons are gained or lost in the following half-reaction? Cl₂ → 2 Cl^-

About Science

Particles of Matter

Elements of Chemistry

Subatomic Particles

The Atomic Nucleus

How Atoms Bond

How Molecules Mix

How Water Behaves

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Acids and Bases in Our Environment

Organic Compounds

Nutrients of Life

Medicinal Chemistry

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Exam 11: Oxidations and Reductions Charge the World

Why is the anode of a battery indicated with negative (-)sign?

How many electrons are gained or lost in the following half-reaction? Zn → Zn2+

The general chemical equation for photosynthesis is shown below. Through this reaction, are the oxygens in the water molecules, H2O, oxidized or reduced? 6 + 6 O → + 6

How many electrons are gained or lost in the following half-reaction? C → C4-

Consider the following molecules. What is the relationship between the degree to which the molecule is oxidized and its polarity?

Which of the following elements would be most useful for creating a n-type silicon?

Metal ores are isolated from rock by taking advantage of differences in both physical and chemical properties. Cite examples given in the textbook where differences in physical properties are used.

What is the purpose of a salt-bridge?

What is a drawback of roasting metal sulfides?

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

Based on their relative positions in the periodic table, which might you expect to be a stronger oxidizing agent, chlorine or fluorine? Why?

The following set of redox reactions takes place between iron dipped in a solution of copper ions. Fe → Fe2+ + 2e- Cu2+ + 2e- → Cu Which of the following describes what is happening on the surface of the iron?

Why are combustion reactions generally exothermic?

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

Which of the following describes an electrode?

Iron is useful for reducing copper ions to copper metal. Might it also be used to reduce sodium ions to sodium metal?

In one type of fuel cell, the following oxidation-reduction reactions are taking place: 2 H2 + O2 → 2 H2O What is the oxidant?

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn What is being formed at the cathode?

How many electrons are transferred from iron atoms to oxygen atoms in the formation of two units of iron hydroxide, Fe ?

How many electrons are gained or lost in the following half-reaction? Cl2 → 2 Cl-

About Science

Particles of Matter

Elements of Chemistry

Subatomic Particles

The Atomic Nucleus

How Atoms Bond

How Molecules Mix

How Water Behaves

How Chemicals React

Acids and Bases in Our Environment

Organic Compounds

Nutrients of Life

Medicinal Chemistry

Optimizing Food Production

Protection Water and Air Resources

Capturing Energy

Filters

How many electrons are gained or lost in the following half-reaction? Zn → Zn²⁺

The general chemical equation for photosynthesis is shown below. Through this reaction, are the oxygens in the water molecules, H₂O, oxidized or reduced? 6 + 6 O → + 6

How many electrons are gained or lost in the following half-reaction? C → C^4-

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

The following set of redox reactions takes place between iron dipped in a solution of copper ions. Fe → Fe²⁺ + 2e- Cu²⁺ + 2e- → Cu Which of the following describes what is happening on the surface of the iron?

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

In one type of fuel cell, the following oxidation-reduction reactions are taking place: 2 H₂+ O₂ → 2 H₂O What is the oxidant?

In a battery, the following oxidation-reduction reactions are taking place: Mn₂O₃ + ZnO → 2 MnO₂ + Zn What is being formed at the cathode?

How many electrons are gained or lost in the following half-reaction? Cl₂ → 2 Cl^-