Transcript Activity 20 Analysis Questions 1. Analyze each of the models you built. Models of Polymers Type of polymer model Strengths Fits on a desktop. Weaknesses Does not.

Activity 20 Analysis Questions
1. Analyze each of the models you built.
Models of Polymers
Type of polymer model
Strengths
Fits on a desktop.
Weaknesses
Does not show structure of the monomers.
Can be used by one person.
Paper clips linked together
Clearly shows the dif. between a
monomer as one paper clip and a polymer
as a chain of the same unit.
Takes a lot of people to use.
Classmates holding hands
Shows how cross-linking makes it
harder to move the polymer around.
Shows atomic level.
Class molecular model
(Activity 19)
Shows the bonding within each
monomer and between the monomer
molecules (for example, shows the
double bond in the monomer).
Doesn’t show the structure of the
monomers.
It is difficult to build and work with a polymer
with five or more subunits.
The bonds are very rigid.
You cannot use these models to test how
easily a polymer can be poured or stirred.
2. Compare the models you built in this activity.
a. Which was most helpful when you analyzed the
physical properties of a polymer?
• Paper clips handled easily
• Both reflected change in physical properties of
the material as the polymers were cross-linked
• Which gave you a better image of the process?
b. Most helpful when analyzing chemical reactions?
• Different colored paper-clips made it easy to see
polymerization and cross-linking
• Student model showed the double bond in the
vinyl alcohol and the need to break it to form a
polymer.
3. Using examples from this and Activity 19, explain
the relationships between a monomer, a polymer,
and a cross-linked polymer. Include a sketch.
• a monomer is a molecule.
• many monomers linked together with chemical
bonds = polymer
• chemically link polymers together = cross-linked
polymer
Monomer
Polymer
Cross-linked polymer
4. How does cross-linking affect the properties of a
polymer?
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becomes harder, thicker, more difficult to pour
5. Based on observations, what advantages do you
think polymers have on monomers?
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monomers are individual units
means they move around easily
aren’t held together in any way
polymers are connected units
means they are flexible and bend
also have strength of molecules joined together
being polymers, may give plastics their strength and
flexibility.
Activity 21
Title: Polymer Parts
What are the properties of polyvinyl
alcohol and sodium borate, as well as
the physical properties of the product
that resulted when you combined
them (Activity 19)?
• Viscosities are very different
• Viscosities of the models were different
(viscosity: resistance of a liquid to sheer
forces (and therefore to flow)
What does the prefix “poly-” in
polyvinyl alcohol indicate?
• It is a polymer
• It is made up of many repeating
monomers of molecules
What was the purpose of the sodium
borate?
• The sodium borate provided the links to
form a cross-linked polymer.
Was this a physical or a
chemical change?
• The thickness of the substance changed
• The color of the final product is cloudy
• These are two physical changes that
indicate a chemical reaction occurred.
• Both physical and chemical change took
place.
Key Terms
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Monomer
Polymer
Cross-Link
Reactants
Products
Chemical Reaction: B-49
Look at Activity 12
Transparency 12.1, “Graphing Data About
Aluminum, Plastic, and Glass.”
• Aluminum: easy and inexpensive to recycle
• Glass: more difficult and more expensive
• Chemical properties made the process for
breaking down each container type different.
• Cross-Linked polymers are very difficult if
not impossible to break down, making
recycling difficult.
Doing Activity 21
• Read as a group pages B-47 to B-49
• Each person take turns reading a
paragraph out loud
• Technical reading can be difficult, help
each other with the pronunciation of
chemical names
• Fill in “Three-Level Reading Guide:
Polymer Parts” together
• Make sure to discuss your choices
Three-Level Read Guide: Polymer Parts
3. Check the statements below that you agree
with and be ready to support your choices
with ideas from the reading and from your
own knowledge.
cross out the words “be ready to”
For parts a and b, explain whether you
agree or disagree and support your choices
as mentioned above.