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%
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.
59) When metals react with oxygen, they form
A) oxygen gas.
B) noble gases.
C) oxides.
D) nonmetals.
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.
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)
62) Approximately what percentage of the earth’s crust is composed of oxygen?
A) ≈ 5%
B) ≈ 40%
C) ≈ 50%
D) ≈ 75%
63) Which substance is a common oxidizing agent?
A) C
B) Na2Cr2O7
C) N2
D) K
64) Which of the following is NOT a common oxidizing agent?
A) iodine
B) chlorine
C) ozone
D) an antioxidant
65) Antiseptics are substances that
A) are pain killers.
B) kill microorganisms.
C) relieve inflammation.
D) are the same as anesthetics.
66) Given their mode of action, antiseptics are generally best classified as
A) oxidizing agents.
B) reducing agents.
C) acids.
D) bases.
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.
68) Benzoyl peroxide, used in the treatment of acne, is
A) an acid.
B) a base.
C) an oxidizing agent.
D) a reducing agent.
69) Most household bleaches act as
A) oxidizing agents.
B) reducing agents.
C) electron donors.
D) proton donors.
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.
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.
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).
73) Which of the following is a reducing agent?
A) an antioxidant
B) an antiseptic
C) a bleach
D) a disinfectant
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.
75) Which substance is a common reducing agent used in the production of metals from ores?
A) C
B) Na2Cr2O7
C) H2O
D) LiBr
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.
77) 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+.
78) The “white” areas in a black-and-white “positive” print contain
A) silver metal.
B) no silver metal.
C) fixer.
D) silver salts.
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.
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.
81) Antioxidants are
A) oxidizing agents found in foods.
B) reducing agents found in foods.
C) fat-soluble.
D) water soluble.
82) All of the following are reducing agents EXCEPT
A) antioxidants.
B) coal (coke).
C) hydrogen.
D) chlorine.
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
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.
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.
86) Which of the following is NOT a common reducing agent?
A) hydrogen peroxide
B) hydrogen
C) an antioxidant
D) coal/coke
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.
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.
89) Which metal is contained in the TAML family of catalysts?
A) Cd
B) Pd
C) Fe
D) Mn
90) The only natural process that produces oxygen is
A) growth.
B) photosynthesis.
C) humidity.
D) electrochemical cells.
91) Human cells obtain energy by
A) oxidizing carbohydrates.
B) reducing proteins.
C) reducing carbon dioxide.
D) absorbing sunlight.
92) Bread and potatoes are a source of
A) carbohydrates.
B) zinc.
C) magnesium.
D) water.
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.
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.
95) Photosynthesis involves the
A) reduction of carbohydrates.
B) reduction of water.
C) oxidation of water.
D) oxidation of carbohydrates.
8.2 True/False Questions
1) An oxidation reaction often occurs without a corresponding reduction reaction.
2) When a metal reacts with a nonmetal, the metal is oxidized.
3) Zinc is oxidized in the following reaction:
Zn + 2 H+ → Zn2+ + H2
4) If the oxidation number of an atom decreases, the atom has undergone oxidation.
5) An oxidizing agent is reduced.
6) In an electrochemical cell, oxidation takes place at the cathode.
7) A common use of lead storage batteries is automobiles.
8) Corrosion is caused by the reduction of metals.
26
9) An explosion is a rapid chemical reaction that results in a considerable increase in volume.
10) The destructive power generated by an explosive mixture results from the rapid expansion of gaseous
products.
11) Pure oxygen is obtained by liquefying air and then boiling off the nitrogen and argon.
12) Naturally occurring reactions of oxygen (O2) are always desirable.
13) Bleach is an oxidizing agent.
14) Palladium metal can absorb up to 900 times its own volume of hydrogen.
15) In Food Chemistry, reducing agents are sometimes referred to as antioxidants.
16) A catalyst acts by raising the amount of energy available for a reaction to occur.
17) Specialty chemicals are generally much simpler than industrial chemicals.
18) Many traditional oxidation methods are environmentally harmful.
8.3 Short Answer Questions
1) The air that we breathe is composed of approximately ________% oxygen by volume.
2) Over 20 billion kg of pure oxygen are produced industrially in the United States each year. The source
of this oxygen is ________.
8.4 Essay Questions
1) 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.