23.4
Lesson 23.4 Polymers
Objectives
Lesson Links
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23.4.1 Describe how addition polymers are formed. 2
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3.4.2 Describe how condensation polymers are formed.
Ch. 23 Core TR: Section 4 Review
Chapter 23 Online Student Edition
23.4 Lesson Overview (PowerPoint file)
Study WB Chapter 23 Lesson 4
Overview/Materials
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Overview
Standard
In this lesson you will cover the formation and uses for some common
addition and condensation polymers.
Classroom Materials
1
Block
0.5
Build Background: disposable baby diaper, nylon stockings, and PVC
pipe or pictures of the items
Addition Polymers: samples of items composed of addition polymers
Addition Polymers: metal-link chain, paper clips
Condensation Polymers: 5% aqueous solution of 1,6-hexanediamine,
small beaker, 20% sodium hydroxide, dropper, 5% solution of adipoyl
chloride in cyclohexane, forceps or tongs, water, paper towel
Standard
There are no items.
Chemistry & You
Description
Engage
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Chapter 23 Online Student
Edition
Have students study the Chemistry & You
feature on p. 822. Relate the construction
of a skydiver chain to the formation of a
polymer.
Ask What is the repeating unit, or monomer,
in the chain? (each person in the chain)
Ask What do you think are some of the
characteristics of monomers? (Answers will
vary. Students may suggest that monomers
must have the ability to be joined together,
must be small molecules or must be
chemically reactive.)
Build Background
Description
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Engage
Bring in samples or show students pictures
of a disposable baby diaper, nylon
stockings, and PVC pipe. Explain that each
of these are everyday items made of
polymers.
Materials: disposable baby diaper, nylon
stockings, and PVC pipe or pictures of the
items
Addition Polymers
Description
Explain
Discuss the similarities between the addition
of hydrogen and halogens to alkenes and
the formation of addition polymers. Explain
that chemists have also found that when
certain catalysts are used, alkenes will add
to one another to form a long chain of
hydrocarbon units.
Ask What is a catalyst? (A catalyst is a
substance that increases the rate of a
reaction without being used up in the
reaction.)
Write the formula for the simplest repeating
unit of a polymer on the board. Ask
students to identify the polymer and to write
out the structure for the polymer showing
how three successive monomers are linked
together.
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Content
Chapter 23 Online Student
Edition
Ask Why can't we write an exact formula for
a polymer? (The length of the carbon chain
varies from polymer molecule to polymer
molecule. The best that can be done is to
write the formula for the simplest repeating
unit, the monomer, in parentheses. The
subscript x indicates a very large number.)
Have students study the chemical equations
for the formation of the addition polymers
discussed on p. 822-824. Write the
equations on the board and help students
identify the repeating units. Discuss the
features of an addition polymerization and
how the name of a polymer is derived from
the monomer units. Bring to class samples
of items that are composed of addition
polymers. Have students describe and
compare their physical characteristics.
Ask What are some of the advantages of
synthetic polymers over metals and other
natural materials? (They are moldable,
lightweight, chemically resistant, and easy to
clean.)
Materials: samples of items composed of
addition polymers
Addition Polymers
Description
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Extend
Have students write a paragraph comparing
and contrasting the chemistry concept of
polymers and monomers to the
mathematical concept of polynomials and
monomials. Encourage students to use
diagrams as well as words to describe their
analogy.
Addition Polymers
Description
Explore
Use a teacher demonstration to help
students better understand how monomers
link together to form polymers.
Bring a length of metal-link chain to class.
Use the metal chain as a model for a
polymer. Explain that a polymerization
reaction is a reaction that joins monomers
to form a polymer. Point out the features in
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the chain that are similar to a polymer
molecule. In addition, model a
polymerization reaction using paperclips.
Each paperclip represents a monomer.
Explain that each end of the paperclip
represents a reaction site. Build a chain by
successively connecting one paperclip to
another. The chain formed is analogous to
a polymer. Point out that the main
differences between polymers in organic
chemistry are due to the type of monomers
used to form the chains.
Materials: metal-link chain, paper clips
Condensation Polymers
Description
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Explain
Explain that the key to polymerization is the
ability of molecules to form repeating chains.
For this to happen, each reacting molecule
must have at least two reactive sites. In
addition polymerization, the two active sites
become available as double bonds are
opened up. In condensation polymerization,
the sites become available as two groups (
such as —H and —OH groups) are split off
the molecules.
Condensation Polymers
Description
Extend
Have students research the use of synthetic
polymers in medicine. Some applications
include prosthetics, skin substitutes, artificial
artery grafts, and heart valve replacements.
Condensation Polymers
Description
Explore
Use a teacher demonstration to show
students the synthesis of nylon.
Pour 5 mL of a 5% aqueous solution of 1,6-
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hexanediamine into a small beaker. Add 5
drops of 20% sodium hydroxide. Slowly
pour 5 mL of a 5% solution of adipoyl
chloride in cyclohexane down the wall of the
beaker. A two-phase system will form, and
a polymer film will appear at the interface.
Use forceps or tongs to slowly draw out a
long strand of nylon. Rinse thoroughly with
water and set it on a paper towel to dry.
Have students examine the color, hardness,
and strength. Discuss the uses of nylon,
and explain that it is a polyamide and a
condensation polymer.
Safety
Wear safety goggles, a chemical-resistant
apron, and chemical resistant gloves while
preparing solutions and performing the
demonstration.
Materials
5% aqueous solution of 1,6-hexanediamine,
small beaker, 20% sodium hydroxide,
dropper, 5% solution of adipoyl chloride in
cyclohexane, forceps or tongs, water,
paper towel
Assess and Remediate
Description
Evaluate
Have students write sentences, in their own
words, describing what takes place during
the formation of a polymer.
Ask What is the difference between an
addition polymer and a condensation
polymer? Give examples of each. (An
addition polymer is formed when
unsaturated monomers react to form a
polymer. One example is the reaction of
ethene to form polyethylene. Condensation
polymers are formed by the head-to-tail
joining of monomer units. The other product
of the condensation reaction is a small
molecule such as water. An example of a
condensation polymer is polyester.)
Then, have students complete the 23.4
Lesson Check.
Remediate
Remind students that the area of chemistry
devoted to the study of polymers involves
more than just plastics. Synthetic fibers are
used to create clothing, automobile tires,
and materials used in the medical and
dental fields. Guide students to examine the
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Resources
Content
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Chapter 23 Online Student
Edition
structures throughout the lesson and then
have students describe the uses of some
addition and condensation polymers.
Chapter 23 Review
Description
Choose from the chapter review and
assessment resources for Chapter 23:
Functional Groups listed at the right.
Resources
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Content
Ch. 23 Problem Set
Content
Ch. 23 Core TR: Practice
Problems
Content
Ch. 23 Core TR:
Interpreting Graphics
Content
Ch. 23 Core TR:
Vocabulary Review
Content
Ch. 23 Core TR: Chapter
Quiz
Content
Ch. 23 Core TR: Chapter
Test A
Content
Ch. 23 Core TR: Chapter
Test B
Differentiated Instruction
Description
Less Proficient Readers
Have students collect several household
items composed of different polymer
materials. Ask them to create a table listing
the items and the plastic container codes
found on the bottom of each item. Have
students do research to find out how the
codes are involved in recycling.
Struggling Students
Have student pairs create ball-and-stick
models for the reactants of each reaction
described in the lesson. Have students
manipulate the models to form the products
of the reactions by removing the appropriate
molecules and creating new bonds.
Advanced Students
Have students do research on the
pioneering work of Elias James Corey, a
Harvard University professor and Nobel
Prize-winning organic chemist. Tell
students that his work led to the synthesis of
more than 100 important drugs and other
naturally occurring compounds. Ask
students to write a short report on their
findings.
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Resources
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Content
Study WB Chapter 23
Lesson 4
Content
Ch. 23 Core TR:
Vocabulary Review
Content
Ch. 23 Core TR: Section
4 Review
Focus on ELL
Description
Comprehensible Input
Write the product of the first addition
polymer on p. 822 on the board, and
beside it, write the condensed structural
formula for butane. Erase the parentheses
and parenthetical subscripts for each, and
write them in a contrasting color. Use the
two formulas to demonstrate how the
parentheses and their accompanying
subscript indicate the presence of multiple
identical units within each molecule.
My Notes
page 7 of 7
Resources
Pacing
Content
Chapter 23 Online Student
Edition
Content
Study WB Chapter 23
Lesson 4
Content
Ch. 23 Core TR:
Vocabulary Review
Content
Ch. 23 Core TR: Section
4 Review
Homework