Ch 8 REDOX
69) Most household bleaches act as A) oxidizing agents. B) reducing agents. C) electron donors. D) proton donors.
a
73) Which of the following is a reducing agent? A) an antioxidant B) an antiseptic C) a bleach D) a disinfectant
a
75) Which substance is a common reducing agent used in the production of metals from ores? A) C B) Na2Cr2O7 C) H2O D) LiBr
a
76) 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.
a
The air that we breathe is composed of approximately ________% oxygen by volume.
21
When your car rusts, the major chemical reaction is between the iron from the steel in the car body with the oxygen from the air to form iron(III) oxide. Write and balance the chemical equation.
4 Fe + 3 O2 → 2 Fe2O3
10) 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.
a
13) 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.
a
15) What is reduced in the following reaction? 2 Bi3+ + 3 Mg → 2 Bi + 3 Mg2+ A) Bi3+ B) Mg C) Bi D) Mg2+
a
19) In the reaction Cu^+ + Fe → Cu + Fe^2+ (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.
a
22) Which substance is a reducing agent? A) C B) I2 C) H2O2 D) TeO2
a
3) The oxidation number of F-1 is A) -1. B) 0. C) +1. D) 2.
a
31) An electrochemical cell is a device that converts chemical energy into A) electrical energy. B) chemical energy. C) nuclear energy. D) light energy.
a
32) 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.
a
33) A battery is a device that converts chemical energy into A) electrical energy. B) chemical energy. C) nuclear energy. D) light energy.
a
38) 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.
a
39) 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
a
49) 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.
a
54) ________ is used as an explosive and a heart medication. A) Nitroglycerin B) Trinitrotoluene C) Ammonia nitrate D) Urea
a
55) All of the following are commonly involved in explosions EXCEPT A) aluminum metal. B) ammonium nitrate. C) nitroglycerin. D) trinitrotoluene.
a
56) The most abundant element (by mass) in the human body is A) oxygen. B) carbon. C) nitrogen. D) water.
a
6) The carbon in C2H6O2 is ________ in the following reaction: C2H6O2 → C2H4O2 + H2 A) oxidized B) reduced C) neutralized D) electrolyzed
a
60) 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.
a
66) Given their mode of action, antiseptics are generally best classified as A) oxidizing agents. B) reducing agents. C) acids. D) bases.
a
8) 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
a
86) Which of the following is NOT a common reducing agent? A) hydrogen peroxide B) hydrogen C) an antioxidant D) coal/coke
a
87) All of the following are true for green oxidation catalysts EXCEPT A) they are often carcinogenic. B) they often rely on transition metals. C) they often allow reactions to run at lower temperatures. D) they are more efficient than traditional catalysts.
a
91) Human cells obtain energy by A) oxidizing carbohydrates. B) reducing proteins. C) reducing carbon dioxide. D) absorbing sunlight.
a
92) Bread and potatoes are a source of A) carbohydrates. B) zinc. C) magnesium. D) water.
a
Over 20 billion kg of pure oxygen are produced industrially in the United States each year. The source of this oxygen is ________.
air
1) 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.
b
11) All redox reactions occur with the transfer of A) protons. B) electrons. C) chlorine. D) nitrogen.
b
2) 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.
b
20) Which substance is an oxidizing agent? A) NaOH B) H2O2 C) HI D) LiBr
b
25) In the reaction Fe2O3 + 3 H2 → 2 Fe + 3 H2O, the reducing agent is A) Fe2O3. B) H2. C) Fe. D) H2O.
b
26) 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.
b
29) 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.
b
34) A major advantage of lead storage batteries is that they are A) lightweight. B) rechargeable. C) disposable. D) all of the above
b
36) A substance that is produced as a lead-acid storage battery generates an electric current is A) Pb. B) PbSO4. C) PbO2. D) H2SO4.
b
41) 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.
b
43) The corrosion of metals, such as the rusting of iron, is an example of A) reduction. B) oxidation. C) proton transfer. D) transmutation.
b
44) 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.
b
47) 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.
b
48) 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.
b
50) Roughly ________% of all iron and steel produced each year is used to replace corroded items. A) 4 B) 20 C) 50 D) 75
b
51) Most chemical explosions are ________ reactions. A) nuclear fission B) oxidation-reduction C) neutralization D) condensation
b
52) 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.
b
57) 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%
b
63) Which substance is a common oxidizing agent? A) C B) Na2Cr2O7 C) N2 D) K
b
65) Antiseptics are substances that A) are pain killers. B) kill microorganisms. C) relieve inflammation. D) are the same as anesthetics.
b
67) 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.
b
7) 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
b
70) The active ingredient in many laundry bleaches and bleaching powders is A) hydrogen peroxide, H2O2. B) hypochlorite ion, ClO-. C) sodium dichromate, Na2Cr2O7. D) chlorine, Cl2.
b
71) 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.
b
80) 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.
b
81) Antioxidants are A) oxidizing agents found in foods. B) reducing agents found in foods. C) fat-soluble. D) water soluble.
b
84) Nickel, platinum, and palladium are used as catalysts for reactions for hydrogen. These metals have A) great catalytic activity and not much of surface area, so hydrogen absorbed on the surface of these metals is less reactive than ordinary hydrogen gas. B) great catalytic activity and lots of surface area, so hydrogen absorbed on the surface of these metals is more reactive than ordinary hydrogen gas. C) little catalytic activity and lots of surface area, so hydrogen absorbed on the surface of these metals is more reactive than ordinary hydrogen gas. D) great catalytic activity and lots of surface area, so hydrogen absorbed on the surface of these metals is less reactive than ordinary hydrogen gas.
b
9) 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
b
90) The only natural process that produces oxygen is A) growth. B) photosynthesis. C) humidity. D) electrochemical cells.
b
93) In the photosynthesis reaction: 6 CO2 + 6 H2O → C6H12O6 + 6 O2, carbon dioxide is A) oxidized. B) reduced. C) oxidized and reduced. D) neither oxidized nor reduced.
b
94) In the photosynthesis reaction: 6 CO2 + 6 H2O → C6H12O6 + 6 O2, the substance that serves as the reducing agent is A) carbon dioxide. B) water. C) sunlight. D) glucose, C6H12O6.
b
FYI 88) The HPPO process utilizes hydrogen peroxide and propylene oxide. One aspect of the HPPO process that is NOT true is A) the reaction is run in aqueous methanol. B) Ti is rare and toxic. C) the methanol used can be recycled. D) it uses a titanium silicate catalyst.
b
12) 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.
c
14) The oxidation number for l in l2 is A) -2. B) -1. C) 0. D) +1.
c
16) What is the oxidation number of bismuth in Bi2O3? A) +1 B) +2 C) +3 D) +6
c
23) In a reaction, the substance undergoing reduction serves as the A) electron donor. B) proton donor. C) oxidizing agent. D) reducing agent.
c
30) 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.
c
35) 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
c
37) A substance that is reduced as a lead-acid storage battery generates an electric current is A) Pb. B) PbSO4. C) PbO2. D) H2SO4.
c
42) 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.
c
53) 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.
c
59) When metals react with oxygen, they form A) oxygen gas. B) noble gases. C) oxides. D) nonmetals.
c
62) Approximately what percentage of the earth's crust is composed of oxygen? A) ≈ 5% B) ≈ 40% C) ≈ 50% D) ≈ 75%
c
68) Benzoyl peroxide, used in the treatment of acne, is A) an acid. B) a base. C) an oxidizing agent. D) a reducing agent.
c
72) 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).
c
74) In the reaction N2 + 3 H2 → 2 NH3, nitrogen is A) a product. B) a reducing agent. C) an oxidizing agent. D) a catalyst.
c
79) 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.
c
85) Which of the following is NOT true of hydrogen? A) It can form an ion with a +1 charge. B) It can form an ion with a -1 charge. C) It is usually found as free hydrogen and not combined with other elements. D) It is a colorless, odorless gas.
c
89) Which metal is contained in the TAML family of catalysts? A) Cd B) Pd C) Fe D) Mn
c
95) Photosynthesis involves the A) reduction of carbohydrates. B) reduction of water. C) oxidation of water. D) oxidation of carbohydrates.
c
58) 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.
c, iron 3 oxide is Fe2O3
17) 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
d
18) Sodium bisulfite converts bromine (Br2) to bromide (Br-). Sodium bisulfite is a(n) A) acid. B) base. C) oxidizing agent. D) reducing agent.
d
21) Hydrogen gas converts tungsten oxide to tungsten metal. Hydrogen (H2) is a(n) A) acid. B) base. C) oxidizing agent. D) reducing agent.
d
24) In the following reaction, hydrogen is the ________. CuO + H2 → Cu + H2O A) electron donor B) proton donor C) oxidizing agent D) reducing agent
d
27) 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.
d
28) 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.
d
4) When C3H8 is burned in oxygen, the products are A) C + H2. B) CH2 + H2O. C) CO2 + H2. D) CO2 + H2O.
d
40) 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
d
45) The black tarnish on silver is A) AgOH. B) Ag2O. C) AgCl. D) Ag2S.
d
46) 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
d
5) 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
d
61) 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)
d
64) Which of the following is NOT a common oxidizing agent? A) iodine B) chlorine C) ozone D) an antioxidant
d
82) All of the following are reducing agents EXCEPT A) antioxidants. B) coal (coke). C) hydrogen. D) chlorine.
d
83) When hydrogen is added to a compound, which of the following can act as a catalyst? A) P B) C C) S D) Pd
d
A catalyst acts by raising the amount of energy available for a reaction to occur.
f
An oxidation reaction often occurs without a corresponding reduction reaction.
f
Corrosion is caused by the reduction of metals
f
If the oxidation number of an atom decreases, the atom has undergone oxidation.
f
In an electrochemical cell, oxidation takes place at the cathode.
f
Naturally occurring reactions of oxygen (O2) are always desirable.
f
Specialty chemicals are generally much simpler than industrial chemicals.
f
A common use of lead storage batteries is automobiles.
t
An explosion is a rapid chemical reaction that results in a considerable increase in volume.
t
An oxidizing agent is reduced.
t
Bleach is an oxidizing agent.
t
In Food Chemistry, reducing agents are sometimes referred to as antioxidants.
t
Many traditional oxidation methods are environmentally harmful.
t
Palladium metal can absorb up to 900 times its own volume of hydrogen.
t
Pure oxygen is obtained by liquefying air and then boiling off the nitrogen and argon.
t
The destructive power generated by an explosive mixture results from the rapid expansion of gaseous products.
t
When a metal reacts with a nonmetal, the metal is oxidized.
t
Zinc is oxidized in the following reaction: Zn + 2 H+ → Zn2+ + H2
t