Problem set

Please label the problems with the given numbers to avoid confusion.

21. Butadiene, H2C ===CH----CH==CH2, is polymerized to make buna rubber.
Write an equation representing this process. Is this am example of
addition or condensation polymerization?

23. Kevlar is a type of nylon called an aramid that contains aromatic
rings. Because of its great mechanical strength, Kevlar is used in
radial tires. The two monomers for producing Kevlar are these.

Monomer A

O O

^ ^

H-O-C ---- (a pentagon) ---- C – O – H

Monomer B

H H

\ /

N ---- (a pentagon) ---- N

/ \

H H

When these two monomers join, what linkage between monomers forms the
resulting polymer?

26. What are the relationships among these terms?

Natural, synthetic, polymers, nylon, protein

Show these relationships by writing an outline with enough information
to show how the terms are related.

31a. Consider the polymerization of a thousand ethylene monomers to form
a large segment of polyethylene.



1000 H C===CH -( -(-CH CH -)-

2 2 2 2 1000

Calculate the energy change during this reaction. (Use the table below.)

H C N O S

H 436

C 416 356

N 391 285 160

O 467 336 201 146

S 347 272 226

H C N O S F C1 Br I

F 566 485 272 190 326 158

C1 431 327 193 205 255 255 242

Br 366 285 234 213 217 193

1 299 213 201 209 180 151

Multiple Bonds

C== 598

C(3 lines)C 813

N(2lines) 418

N (3 lines) 946

C(2 lines)N 616

C(3 lines)N 866

O(2 lines)O 498

C(2 lines)) 803 in CO2

C(3 lines)O 1073

33. When you try to stretch a piece of plastic bag, the length of the
piece of plastic being pulled increases dramatically and the thickness
decreases. Does the same thing happen when you pull on a piece of paper?
Why or why not? Explain on a molecular level.