Deck 8: Oxidation and Reduction

Question 1

Which of the following is a definition of oxidation?

A) Oxidation is the loss of electrons.
B) Oxidation is the addition of hydrogen.
C) Oxidation is the loss of oxygen.
D) Oxidation is the addition of electrons.

Answer 1

Oxidation is the loss of electrons.

Question 2

The black, granular material that fills a dry cell in a common flashlight (between the carbon rod and the zinc shell) is manganese(II) oxide, MnO₂. The oxidation number of manganese in MnO₂ is

A) +2.
B) -2.
C) +4.
D) -4.

Answer 2

+4.

Question 3

Sodium bisulfite converts bromine (Br₂) to bromide (Br^-). Sodium bisulfite is a(n)

A) acid.
B) base.
C) oxidizing agent.
D) reducing agent.

Answer 3

reducing agent.

Question 4

Which of the following is a definition of reduction?

A) Reduction is the gain of oxygen.
B) Reduction is the gain of hydrogen.
C) Reduction is the loss of hydrogen.
D) Reduction is the gain of BOTH electrons AND oxygen.

Question 5

All redox reactions occur with the transfer of

A) protons.
B) electrons.
C) chlorine.
D) nitrogen.

Question 6

Consider the following unbalanced half-reaction: MnO₄^- → MnO₂. The oxidation number of Mn changes from ________, and the Mn is ________.

A) +4 to +7; reduced
B) +7 to +4; oxidized
C) +4 to +7; oxidized
D) +7 to +4; reduced

Question 7

Which substance is an oxidizing agent?

A) NaOH
B) H₂O₂
C) HI
D) LiBr

Question 8

What is the oxidation number of bismuth in Bi₂O₃?

A) +1
B) +2
C) +3
D) +6

Question 9

In which of the following is the reactant undergoing oxidation? (Note: These reactions are not complete chemical equations.)

A) Cl₂ → 2 Cl^-
B) WO₃ → W
C) 2 H⁺ → H₂
D) C → CO₂

Question 10

Consider the following unbalanced equation between copper(I) ions and iron to produce copper metal and iron(II) ions: Cu⁺ + Fe → Cu + Fe²⁺ What is oxidized in this reaction?

A) copper(I) ion
B) iron
C) copper
D) iron(II) ion

Question 11

What is reduced in the following reaction? 2 Bi³⁺ + 3 Mg → 2 Bi + 3 Mg²⁺

A) Bi³⁺
B) Mg
C) Bi
D) Mg²⁺

Question 12

In the reaction Cu⁺ + Fe → Cu + Fe²⁺ (Note: The reaction is not balanced.)

A) Fe is the reducing agent.
B) Cu is the reducing agent.
C) Cu⁺ is the reducing agent.
D) Fe²⁺ is the reducing agent.

Question 13

The carbon in C₂H₆O₂ is ________ in the following reaction: C₂H₆O₂ → C₂H₄O₂ + H₂

A) oxidized
B) reduced
C) neutralized
D) electrolyzed

Question 14

The oxidation number of F^-1 is

A) -1.
B) 0.
C) +1.
D) 2.

Question 15

Every reduction reaction MUST be accompanied by

A) an oxidation reaction.
B) formation of ionic bonds.
C) formation of triple bonds.
D) formation of oxygen.

Question 16

The oxidation number for l in l₂ is

A) -2.
B) -1.
C) 0.
D) +1.

Question 17

With respect to energy content, reduced forms of matter are generally

A) low in potential energy and often make good fuels.
B) high in potential energy and often make good fuels.
C) low in potential energy and are poor fuels.
D) high in potential energy and are poor fuels.

Question 18

In which of the following is the reactant undergoing reduction? (Note: These reactions are not complete chemical equations.)

A) C₂H₄O → C₂H₄O₂
B) C₂H₄O → C₂H₆O
C) CO → CO₂
D) CH₄ → C

Question 19

In which of the following partial reactions is the reactant undergoing reduction? (Note: The reactions are not complete.)

A) PbO → Pb
B) KClO₂ → KClO₃
C) SnO → SnO₂
D) Cu₂O → CuO

Question 20

When C₃H₈ is burned in oxygen, the products are

A) C + H₂.
B) CH_{2 +} H₂O.
C) CO₂ + H₂.
D) CO₂ + H₂O.

Question 21

In the following reaction, hydrogen is the ________. CuO + H₂ → Cu + H₂O

A) electron donor
B) proton donor
C) oxidizing agent
D) reducing agent

Question 22

Consider the following reaction: 2 Fe + 3 Mg²⁺ → 2 Fe³⁺ + 3 Mg The half-reaction for the oxidation in this reaction is

A) Fe → Fe³⁺ + 3 e^-
B) Fe³⁺ + 3 e^- → Fe
C) Mg → Mg²⁺ + 2 e^-
D) Mg²⁺ + 2 e^- → Mg

Question 23

Copper is plated on zinc by immersing a piece of zinc into a solution containing copper(II) ions. In the plating reaction, copper(II) ions

A) lose two electrons and are oxidized.
B) lose two electrons and are reduced.
C) gain two electrons and are oxidized.
D) gain two electrons and are reduced.

Question 24

Silver is plated on copper by immersing a piece of copper into a solution containing silver ions. In the plating reaction, silver ions

A) are oxidized and are the oxidizing agent.
B) are oxidized and are the reducing agent.
C) are reduced and are the oxidizing agent.
D) are reduced and are the reducing agent.

Question 25

Hydrogen gas converts tungsten oxide to tungsten metal. Hydrogen (H₂) is a(n)

A) acid.
B) base.
C) oxidizing agent.
D) reducing agent.

Question 26

A substance that is produced as a lead-acid storage battery generates an electric current is

A) Pb.
B) PbSO₄.
C) PbO₂.
D) H₂SO₄.

Question 27

In the reaction Fe₂O₃ + 3 H₂ → 2 Fe + 3 H₂O, the reducing agent is

A) Fe₂O_3.
B) H_2.
C) Fe.
D) H₂O.

Question 28

A battery is a device that converts chemical energy into

A) electrical energy.
B) chemical energy.
C) nuclear energy.
D) light energy.

Question 29

A substance that is reduced as a lead-acid storage battery generates an electric current is

A) Pb.
B) PbSO₄.
C) PbO₂.
D) H₂SO₄.

Question 30

A device that generates an electrical current by taking advantage of a difference in the spontaneous tendency of substances to lose and gain electrons is called an

A) electrochemical cell.
B) electrolysis cell.
C) electroplating cell.
D) electrolyte cell.

Question 31

Consider the following reaction: 2 Fe + 3 Mg²⁺ → 2 Fe³⁺ + 3 Mg The half-reaction for the reduction in this reaction is

A) Fe → Fe³⁺ + 3 e^-
B) Fe³⁺ + 3 e^- → Fe
C) Mg → Mg²⁺ + 2 e^-
D) Mg²⁺ + 2 e^- → Mg

Question 32

Copper is plated on zinc by immersing a piece of zinc into a solution containing copper(II) ions. In the plating reaction, copper II ions

A) gain two electrons and is are oxidized.
B) gain two electrons and is are reduced.
C) lose two electrons and is are reduced.
D) lose two electrons and is are oxidized.

Question 33

Silver is plated on copper by immersing a piece of copper into a solution containing silver ions. In the plating reaction, silver ions

A) lose one electron and are oxidized.
B) lose one electron and are reduced.
C) gain one electron and are oxidized.
D) gain one electron and are reduced.

Question 34

Which of the following statements is true for electrochemical cells?

A) Oxidation occurs at the anode.
B) Oxidation occurs at the cathode.
C) Reduction occurs at the anode.
D) Both oxidation and reduction occur at the cathode.

Question 35

In a reaction, the substance undergoing reduction serves as the

A) electron donor.
B) proton donor.
C) oxidizing agent.
D) reducing agent.

Question 36

The small "button" cells used in hearing aids and hand calculators are being replaced by ________ cells.

A) Ni-Cad
B) hydrogen
C) zinc-air
D) copper-acid

Question 37

A major advantage of lead storage batteries is that they are

A) lightweight.
B) rechargeable.
C) disposable.
D) all of the above

Question 38

Silver is plated on copper by immersing a piece of copper into a solution containing silver ions. In the plating reaction, copper

A) is oxidized and is the oxidizing agent.
B) is oxidized and is the reducing agent.
C) is reduced and is the oxidizing agent.
D) is reduced and is the reducing agent.

Question 39

Which substance is a reducing agent?

A) C
B) I₂
C) H₂O₂
D) TeO₂

Question 40

An electrochemical cell is a device that converts chemical energy into

A) electrical energy.
B) chemical energy.
C) nuclear energy.
D) light energy.

Question 41

Magnesium burns brightly in the presence of oxygen. When magnesium reacts with oxygen, the compound formed is

A) MgO.
B) MgO₃.
C) Mg₃O.
D) Mg₄O₄.

Question 42

The black tarnish on silver is

A) AgOH.
B) Ag₂O.
C) AgCl.
D) Ag₂S.

Question 43

Roughly ________% of all iron and steel produced each year is used to replace corroded items.

A) 4
B) 20
C) 50
D) 75

Question 44

When metals react with oxygen, they form

A) oxygen gas.
B) noble gases.
C) oxides.
D) nonmetals.

Question 45

Which of the following statements about the rusting of iron is true?

A) Iron is reduced in the presence of oxygen.
B) Iron is oxidized in the presence of oxygen.
C) The iron(III) hydroxide forms a hard coating that protects the iron from undergoing further corrosion.
D) Iron will rust more quickly in the absence of water.

Question 46

Most chemical explosions are ________ reactions.

A) nuclear fission
B) oxidation-reduction
C) neutralization
D) condensation

Question 47

When your car rusts, the major chemical reaction is that between the iron from the steel in the car body with the oxygen from the air to form iron(III) oxide. When the reaction is balanced, the coefficient of iron is

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

Question 48

________ is used as an explosive and a heart medication.

A) Nitroglycerin
B) Trinitrotoluene
C) Ammonia nitrate
D) Urea

Question 49

Aluminum is more reactive than iron, yet it is used today for a variety of applications in which iron would corrode (cans, rain gutters, etc.). The reason for the corrosion durability of aluminum is that

A) aluminum does not react with oxygen.
B) very unreactive aluminum oxide forms a thin layer on aluminum.
C) aluminum does not undergo oxidation.
D) all aluminum products are treated with a plastic coating.

Question 50

ANFO is an explosive mixture of ammonium nitrate, NH₄NO₃, and fuel oil. When this mixture explodes, the ammonium nitrate undergoes

A) oxidation.
B) reduction.
C) both oxidation and reduction.
D) neither oxidation nor reduction.

Question 51

With respect to volume, approximately what percentage of the air we breathe is composed of elemental argon?

A) ≈ 20%
B) ≈ 1%
C) ≈ 80%
D) ≈ 50%

Question 52

Photochromic lenses contain

A) only AgCl embedded in the glass.
B) only CuCl embedded in the glass.
C) both AgCl and CuCl embedded in the glass.
D) neither AgCl nor CuCl embedded in the glass.

Question 53

A mixture of ammonium nitrate (NH₄NO₃) and fuel oil has often been used in terrorist attacks around the world. Which of the following statements is NOT true for this type of explosive mixture?

A) The materials are readily available to the general public.
B) It is very difficult to obtain the ammonium nitrate.
C) The ammonium nitrate serves as both an oxidizing agent and a reducing agent.
D) The reaction results in gaseous products and a huge increase in volume.

Question 54

The most abundant element (by mass) in the human body is

A) oxygen.
B) carbon.
C) nitrogen.
D) water.

Question 55

All of the following are commonly involved in explosions EXCEPT

A) aluminum metal.
B) ammonium nitrate.
C) nitroglycerin.
D) trinitrotoluene.

Question 56

The corrosion of metals, such as the rusting of iron, is an example of

A) reduction.
B) oxidation.
C) proton transfer.
D) transmutation.

Question 57

Aluminum is more reactive than iron is, but iron corrodes more quickly. This occurs because

A) aluminum is reduced in the presence of oxygen while iron is oxidized.
B) aluminum develops a coating of aluminum oxide, which protects it from further reaction.
C) iron is exposed to both oxygen and water, while aluminum is rarely exposed to water.
D) iron has a lower density than aluminum does.

Question 58

When silver tarnishes,

A) Ag atoms are oxidized to form Ag⁺ ions.
B) Ag atoms are reduced to form Ag⁺ ions.
C) Ag⁺ ions are oxidized to form Ag atoms.
D) Ag⁺ ions are reduced to form Ag atoms.

Question 59

A battery in which a fuel is oxidized at the anode and oxygen is reduced at the cathode is a(n)

A) alkaline battery.
B) fuel cell.
C) lead storage battery.
D) lithium battery.

Question 60

The removal of silver tarnish from silverware using aluminum foil and a solution of electrolyte is an example of

A) oxidation of aluminum metal.
B) reduction of silver ions.
C) an electrochemical cell.
D) all of the above

Question 61

A substance which lowers the activation energy of a chemical reaction is called a(n)

A) reducing agent.
B) catalyst.
C) oxidizing agent.
D) carcinogen.

Question 62

The active ingredient in many laundry bleaches and bleaching powders is

A) hydrogen peroxide, H₂O₂.
B) hypochlorite ion, ClO^-.
C) sodium dichromate, Na₂Cr₂O_7.
D) chlorine, Cl₂.

Question 63

In a black-and-white photograph, the black area on the photographic negative represents

A) the region where light fell and silver metal has been deposited during development.
B) the region where light fell and silver metal has been removed during development.
C) a region where light did not fall and silver metal has been deposited during development.
D) a region where light did not fall and silver metal has been removed during development.

Question 64

Approximately what percentage of the earth's crust is composed of oxygen?

A) ≈ 5%
B) ≈ 40%
C) ≈ 50%
D) ≈ 75%

Question 65

Antiseptics are substances that

A) are pain killers.
B) kill microorganisms.
C) relieve inflammation.
D) are the same as anesthetics.

Question 66

Which of the following is a reducing agent?

A) an antioxidant
B) an antiseptic
C) a bleach
D) a disinfectant

Question 67

Which of the following is NOT true of a catalyst?

A) A catalyst will speed up the rate of a reaction.
B) A catalyst will lower the activation energy for a reaction.
C) A catalyst is used up when it catalyzes a reaction.
D) A catalyst is not changed when it catalyzes a reaction.

Question 68

Which of the following is NOT a common oxidizing agent?

A) iodine
B) chlorine
C) ozone
D) an antioxidant

Question 69

An oxidizing agent that was used in older versions of the Breathalyzer test is

A) NaHClO (sodium hypochlorite).
B) O₃ (ozone).
C) K₂Cr₂O₇ (potassium dichromate).
D) AgBr (silver bromide).

Question 70

Swimming pools are "chlorinated" in order to

A) improve taste of the water.
B) disinfect the water.
C) clarify the water.
D) purify the water.

Question 71

The "white" areas in a black-and-white "positive" print contain

A) silver metal.
B) no silver metal.
C) fixer.
D) silver salts.

Question 72

This compound is a powerful oxidizing agent and a harmful pollutant; yet a layer of it in the upper stratosphere serves as a shield from harmful ultraviolet radiation from the sun.

A) CO₂
B) O₂
C) SO₃
D) O₃ (ozone)

Question 73

In the reaction N₂ + 3 H₂ → 2 NH₃, nitrogen is

A) a product.
B) a reducing agent.
C) an oxidizing agent.
D) a catalyst.

Question 74

Which substance is a common oxidizing agent?

A) C
B) Na₂Cr₂O₇
C) N₂
D) K

Question 75

The chemical basis of converting light into a photographic silver image is based on the fact that

A) Ag⁺ exposed to light is easier to reduce to Ag than unexposed Ag⁺.
B) Ag⁺ exposed to light is more difficult to reduce to Ag than unexposed Ag⁺.
C) Ag⁺ exposed to light is easier to oxidize to Ag than unexposed Ag⁺.
D) Ag⁺ exposed to light is more difficult to oxidize to Ag than unexposed Ag⁺.

Question 76

Benzoyl peroxide, used in the treatment of acne, is

A) an acid.
B) a base.
C) an oxidizing agent.
D) a reducing agent.

Question 77

Most household bleaches act as

A) oxidizing agents.
B) reducing agents.
C) electron donors.
D) proton donors.

Question 78

Given their mode of action, antiseptics are generally best classified as

A) oxidizing agents.
B) reducing agents.
C) acids.
D) bases.

Question 79

Which substance is a common reducing agent used in the production of metals from ores?

A) C
B) Na₂Cr₂O₇
C) H₂O
D) LiBr

Question 80

Oxidizing agents are often used

A) as antioxidants.
B) as antiseptics.
C) to form Ag grains in photography.
D) to add hydrogen to an unsaturated fat.