Chapter 2 Review, pages 110–115
Knowledge
1. (c)
2. (b)
3. (c)
4. (a)
5. (a)
6. (c)
7. (d)
8. (c)
9. (d)
10. (d)
11. (a)
12. (d)
13. (a)
14. (a)
15. (c)
16. (a)
17. (a)
18. False. Polymers are large, chain-like molecules built from small molecules called
monomers.
19. True
20. True
21. False. Most plastics are chemically unreactive and virtually indestructible.
22. True
23. True
24. False. Polyamides are polymers formed by condensation reactions resulting in amide
linkages between monomers.
25. False. Examples of natural polymers are carbohydrates, silk, and DNA.
26. (a) (iii)
(b) (vi)
(c) (xi)
(d) (vii)
(e) (i)
(f) (ix)
(g) (ii)
(h) (x)
(i) (v)
(j) (viii)
(k) (iv)
27. A polymer is a very large molecule that is built from monomers.
28. A homopolymer is a polymer formed by reactions involving a single type of
monomer. A copolymer has different types of monomers combined to form the polymer
chain.
29. (a) The compound shown in Figure 1 is 3-bromo-3-chloroprop-1-ene.
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(b)
30. Monomers that permit the formation of cross linkages between polymer chains
increase the rigidity of the polymer.
31. Answers may vary. Sample answer:
Polymer
Example of use
polyvinyl chloride
water pipes
polystyrene
building insulation
HDPE
milk jugs, bottles
LDPE
plastic bags
32. (a) The monomer of Teflon is tetrafluoroethene: F2C=CF2.
(b) The strong C–F bonds are very resistant to chemical change, which makes Teflon
useful for applications such as electrical insulation, non-stick coatings, and low-friction
surface coatings.
33. (a) Phthalates are added as plasticizers to make rigid polymers more flexible.
(b) Health Canada has banned the use of some phthalates in children’s products.
34. (a) A copolymer is a polymer that consists of more than one type of monomer.
(b) The production of nylon involves a condensation polymerization.
(c)
(d) Amide bonds form between monomers during the reaction.
35. (a) Nomex is the product of a condensation reaction.
(b) The by-product is hydrogen chloride.
(c)
36. Dacron is a polyester because the monomers are connected by ester linkages.
37. Water is a common by-product of condensation polymerization.
38. Amide linkages are formed by reactions between amines and carboxylic acids.
39. The structure of the polymer formed by oxirane monomers is:
CH2 CH2 O CH2 CH2 O
40. Answers may vary. Sample answer: Carothers developed nylon, which was designed
to replace silk.
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41. (a) A monosaccharide is a ketone or aldehyde with many additional hydroxyl
substituents.
(b) A polysaccharide is a large polymer consisting of many monosaccharide units.
(c) A carbohydrate is a monosaccharide or a disaccharide.
42. (a) Glycogen is produced by animals to store energy.
(b) Cellulose is produced by plants to provide structure.
(c) DNA is produced by many organisms to pass on genetic information.
43. The cellulose-rich parts of food plants are often used as animal food because certain
animals, such as cattle, can digest it.
44. (a) A protein is a polymer built by condensation reactions between amino acids.
(b) A peptide bond is an amide linkage between 2 amino acids.
(c) DNA is a polymer that stores and transmits genetic information.
45. (a) Nucleotides consist of a 5-carbon sugar, a nitrogen-containing organic base, and a
phosphoric acid molecule.
(b) Nucleotides are esters.
(c) Cytosine and guanine are held together by hydrogen bonds.
(d) These nucleotides contain carbonyl and amine groups, which can form hydrogen
bonds.
Understanding
46. Answers may vary. Sample answer:
An organic chemist may want to determine the chemical structure of spider silk to come
up with a synthetic version, the production of which can be controlled.
47. Answers may vary. Sample answer:
48. Natural polymers are expensive and can be problematic to access. There is a limit to
how much can be produced within a given time.
49. The addition of sulfur creates cross-links between rubber polymers, causing rubber to
become more rigid at high temperatures.
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50. Answers will vary. Sample answer:
(a) name polyethene
polypropene
(b)
monomer
polystyrene
(c)
polymer
(d)
plastic bags
carpet fibres
building insulation
common
use
51. (a) Identify the repeating unit. Replace a single bond between carbons with a double
bond.
(b) Identify the repeating unit. Replace a single bond between carbons with a double
bond.
(c) Identify the repeating unit. Replace a single bond between carbons with a double
bond.
52. The addition of divinylbenzene makes polystyrene more rigid by allowing cross-links
to form between adjacent polymer chains.
53. (a) Plasticizers are additives that increase the flexibility of brittle synthetic polymers.
(b) Phthalates, which are effective plasticizers, have been linked to severe negative health
effects, such as kidney and liver failure. They may also disrupt the human reproductive
system, especially as a result of childhood exposure.
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54. (a) A polymer produced during an addition reaction consists of a chain of carbon
atoms bonded with single bonds.
A condensation polymer contains oxygen or nitrogen atoms between carbon atoms in the
main chain, which indicate the presence of ester or amide linkages, respectively.
(b) To predict the monomer from an addition polymer, (i) determine the repeating units,
and (ii) determine which two carbon atoms in the monomer share a double bond so that
all carbon atoms in the monomer form four bonds.
(c) To predict the monomer from a condensation polymer, (i) determine the repeating
units; (ii) if a nitrogen atom is part of the main carbon chain in the polymer—which
indicates that one or both monomers has an amine functional group—add an H to
complete the amine group and add an ─OH group to complete a different functional
group (carboxyl or hydroxyl); and (iii) if an oxygen atom is part of the main carbon chain
in the polymer—which indicates that the monomers have hydroxyl and/or carboxyl
groups—add an –OH group to complete the carboxyl group and an H to complete the
hydroxyl group.
55. (a) The polymer that forms from pent-2-ene is an addition polymer.
(b) The polymer that forms from1,5-diaminopentane and propane-1,3-diol is a
condensation polymer and a polyamide.
(c) The polymer that forms from 1,5-dichlorohex-2-ene is an addition polymer and a
polyester.
56.
Similarities
Differences
Addition polymers
Condensation polymers
–made up of carbon chains
–natural and synthetic
–no functional groups at
–have a functional group
the ends of the carbon
at one or both ends of the
chain
carbon chain
–formed by breaking of
–small molecules (e.g.,
double bonds between
water) produced as bymonomers
products
–no small molecules
–most natural polymers
produced as by-products
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57. (a) The structure of polylactic acid is:
(b) Water is formed.
(c) Hydrogen bonds would form between PLA chains.
(d) The plastic should be flexible and non-toxic to make it suitable for food packaging.
58. Answers may vary. Sample answer.
Polyesters
Polyamides
Similarities
-condensation polymers
-water produced as by-product
- copolymers
-natural and synthetic
Differences
-one monomer has a
-one monomer has an
hydroxyl group and the
amino group while the
other has a carboxyl group other has a carboxyl group
-formed by esterification
or an acid chloride group
reactions (have ester
-monomers bind together
linkages)
with amide linkages
-produce H2O(l) as a by-produce H2O(l) or
product
HCl(aq) as a by-product
59. (a) Answers will vary. Sample answer:
Synthetic polymers are inexpensive to mass-produce and are very versatile. They can be
made into a wide variety of products that are ubiquitous in our daily lives. This makes
them very useful.
(b) Since synthetic polymers are used so widely and are so inexpensive to produce, there
are huge quantities of them around. Synthetic polymers break down very slowly; so their
disposal is a major problem. In addition, some of them are hormone disruptors and
carcinogens.
60. (a) This sugar is an aldehyde.
(b) A condensation reaction occurs to form the ring structure.
(c)
61. (a) A molecule of hexose contains 6 carbon atoms.
(b) A monosaccharide with 5 carbon atoms is called pentose.
Analysis and Application
62. Answers may vary. Sample answer:
(a) A plastic used to wrap food should be flexible, transparent, and non-toxic.
(b) A plastic used to build the International Space Station should be lightweight yet
durable and also somewhat flexible so it does not shatter when it collides with space
debris.
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(c) There are many different types of plastics with different properties because many
different types of monomers can be combined and processed in a variety of ways.
63. Thermoplastics melt or soften when heated, hold their shape when cooled, and can be
molded. They do not contain many cross-links. Thermoset polymers are highly crosslinked, so they do not soften at high temperatures. Based on these differences,
thermoplastics would be easier to recycle because they can be processed more easily for
new uses.
64. (a) (i)
(ii)
(b) Polymer (ii) would have more hydrogen bonding between its chains because bonds
would form between hydrogen and oxygen and nitrogen atoms on adjacent chains. These
additional linkages between chains would make the polymer more heat stable.
65. (a) Condensation polymers could be made biodegradable by making them using
naturally occurring monomers. If the monomers are naturally occurring, there is likely a
natural process that spontaneously decomposes these monomers and hopefully
decomposes the polymers they form as well.
(b) Problems that could still occur despite the biodegradability of these plastics are
toxicity and contamination. If the smaller chains or monomers are toxic, smaller pieces
could spread more easily, poisoning humans, wildlife, and the environment. The bacteria
used to digest the fragments may also pose a health hazard, especially if they are not
contained.
66. Curls in hair are caused by disulfide bonds. Straight hair can be made curly by adding
a product to it that causes the formation of disulfide bonds within hair strands, and then
twisting the hair around rods while the bonds form.
67. More heat is needed to break G–C pairs because they are held together by 3 hydrogen
bonds, as opposed to 2 hydrogen bonds between the A–T pairs.
68. (a)
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(b) The monomer of starch is glucose.
(c) When you eat a plain unsalted cracker, at first it tastes bland. After chewing for a
short time, it starts to taste sweet. This effect is evidence that saliva is breaking the starch
down into its component glucose, a simple sugar.
Evaluation
69. (a) The monomer for the polymer in Figure 9 (a):
The monomer for the polymer in Figure 9 (b):
(b) Polymer (b) is more rigid because it consists of straight-chain molecules that are
tightly packed. The rigidity of this polymer would make it appropriate for use as
structural material.
70. Answers will vary. Sample answer:
In my opinion, it is more important that plastics be durable and long lasting. That way,
they can be more easily reused for longer time periods, which would decrease the need to
manufacture replacement plastics. Fewer plastics would then need to be discarded.
71. Butan-1,4-diol should be used because it can form a copolymer with
benzene-1,2-dicarboxylic acid. Using propan-1-ol will not result in a polymer because
propan-1-ol has only one hydroxyl group. This prevents propan-1-ol from reacting with
more than one acid molecule and extending the chain.
72. Answer may vary. Sample answer:
(a) Six possible factors to consider include cost of research and development, production
cost, cost of raw materials, demand for product, profit margin, and environmental impact
of product.
(b) The company might rank the importance of these factors in the following order: profit
margin, demand for product, cost of research and development, production cost, cost of
raw materials, environmental impact of product.
(c) I would rank the importance of these factors as follows: environmental impact of
product, demand for product, cost of research and development, production cost, cost of
raw materials, and profit margin.
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(d) I am concerned about the environment, and so the environmental impact and the need
(demand) for the product are most important for me. For a company that needs to stay in
business and keep people employed, profit margin and production cost would be the most
important considerations.
Reflect on Your Learning
73. Answers will vary. Sample answer:
Before studying this chapter, I was aware that there were natural as well as synthetic
polymers, but I didn’t know what exactly a polymer was, nor did I know there were so
many different kinds of polymers.
74. Answers will vary. Sample answer:
After reading this chapter, I am much more aware of the importance of recycling plastics.
Because so much plastic is discarded and because plastics don’t break down easily, I
think it is very important to prioritize research and development of biodegradable
plastics. This way, we won’t run out of room in landfill sites as quickly.
Research
75. Answers may vary. Sample answer:
Carpet recycling is a complex and expensive process. First, an old carpet is scanned for
its polymer content: nylon or polypropene. These polymers are then separated. The long
top fibres are shaved off and spun into recycled yarn. The remaining nylon content is sold
to other companies to be used as nylon plastic for landscaping products, auto parts, and
roof shingles. Cradle-to-cradle carpet recycling programs are very rare in Canada. Most
are located in the United States. In the Greater Toronto Area, there is a carpet recycling
facility in Markham: Sands Commercial Floor Coverings.
76. Answers will vary but could include the following:
• a polymer used as an anode in lithium-ion batteries, which could extend the distance
electric cars could travel and reduce their cost
• a polymer for flooring made from rapidly renewable plant materials, which would
decrease reliance on fossil fuels for raw materials
• “Russian doll” polymer vesicles (vesicles within vesicles) in nanomedicine, which
could deliver several different drugs or active ingredients in a single vesicle
• a polymer that captures nicotine molecules to determine nicotine content of materials in
biomedical and industrial applications
77. Answers may vary. Sample answer:
Poly(glycolic acid) (PGA) and poly(lactic acid) (PLA) are biodegradable polyesters that
break down in the body by way of hydrolysis of the ester linkage. The products of
hydrolysis are non-toxic and non-harmful, and are excreted by the kidneys or eliminated
as carbon dioxide and water. The polymers are currently being used as resorbable
implants and surgical sutures. Researchers are looking for ways to use these polyesters to
encapsulate and deliver drugs.
78. Answers may vary. Sample answer:
To make fabric from milk protein, liquid milk is dried and its proteins are extracted. The
separated milk proteins are dissolved in a chemical solution. Once they are dissolved,
they are placed into a machine that whirls the proteins into fibres. The fibres are then
ready for spinning into yarn and weaving into fabric. Fabric made from milk can be dyed.
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The cloth is breathable and traps moisture; so skin feels smooth and tender, just as after
bathing in milk. On the down side, the fabric is easily wrinkled after being washed and
requires ironing. Clothing made from milk fabric needs to be washed by hand.
Given this information about milk fabric, I would wear milk fabric garments for the
novelty of the experience, but would not buy them if they were expensive.
79. Answers may vary. Sample answer:
I don’t think it is worthwhile to research artificial skin for the sake of making it
bulletproof. However, it would be useful to research artificial skin for medical uses, such
as for burn victims.
80. Answers will vary but could include the following:
- Vitamin A is needed for reforming rhodopsin, a compound on the retina that is needed
for vision in low light
- night blindness is an early sign of vitamin A deficiency
- vitamin A deficiency can dry out the cornea, causing it to become clouded
- corneal dryness can progress to corneal ulcers
- severe deficiency can cause retinal damage, leading to blindness
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