50% (2 out of 4 correct)
The questions marked with
symbol have not been graded.
Responses to questions are indicated by the symbol.
1. Which type(s) of bonds are found between atoms within hydrocarbon
molecules?
A. Ionic bonds
B. Hydrogen bonds
C. Covalent bonds
D. van der Waals bonds
E. Metallic bonds
Covalent bonds are found between atoms within hydrocarbon molecules.
2. What is the name of the hydrocarbon group shown below?
A) ether
B) aromatic hydrocarbon
C) acid
D) alcohol
E) aldehyde
YOUR ANSWER:
B
The suggested answer is
E
The hydrocarbon group shown is an aldehyde.
3. What is the name of the hydrocarbon group shown below?
A) ether
B) aromatic hydrocarbon
C) acid
D) alcohol
E) aldehyde
YOUR ANSWER:
A
The suggested answer is
B
The hydrocarbon group shown is an aromatic hydrocarbon.
4. What is the name of the mer structure shown below?
A) polymethyl methacrylate
B) polyethylene
C) polytetrafluoroethylene
D) polypropylene
E) polystyrene
F) polyvinyl chloride
YOUR ANSWER:
F
The suggested answer is
A
The mer structure shown is for polymethyl methacrylate.
5. What is the name of the mer structure shown below?
A) polymethyl methacrylate
B) polyethylene
C) polytetrafluoroethylene
D) polypropylene
E) polystyrene
F) polyvinyl chloride
YOUR ANSWER:
D
The suggested answer is
D
The mer structure shown is for polypropylene.
6. Which of the following form network polymers?
A. Rubber, polyethylene, and phenol-formaldehyde
B. Epoxy and phenol-formaldehyde
C. Polystyrene and nylon
D. Polyethylene, polystyrene, and nylon
Epoxy and phenol-formaldehyde form network polymers.
7. Name the term used for the configuration of a stereoisomer having R groups
whose positions alternate from one side to the other side along the backbone
chain.
YOUR ANSWER:
polymers
The suggested answer is
syndiotactic
Syndiotactic is the term used for a stereoisomer having R groups whose
positions alternate from one side to the other side along the backbone chain.
8. What name is used for the structural configuration shown below?
YOUR ANSWER:
cipolymers
The suggested answer is
trans
Trans is the term used for the geometric isomer having the two hydrogen
atoms adjacent to the doubly bonded carbon atoms on opposite sides of the
chain.
9. Given the following atomic weights, what is the mer weight (in g/mol) of
polyvinyl chloride?
Carbon
12.01 g/mol
Chlorine
35.45 g/mol
Fluorine
19.00 g/mol
Hydrogen
1.008 g/mol
Oxygen
16.00 g/mol
Silicon
28.09 g/mol
YOUR ANSWER:
368
The suggested answer is
62.49 g/mol
For polyvinyl chloride, each mer unit consists of two carbons, three
hydrogens, and one chlorine; thus the mer weight is
= 62.49 g/mol
10. Given the following atomic weights, what is the mer weight (in g/mol) of
polydimethylsiloxane?
Carbon
12.01 g/mol
Chlorine
35.45 g/mol
Fluorine
19.00 g/mol
Hydrogen
1.008 g/mol
Oxygen
16.00 g/mol
Silicon
28.09 g/mol
YOUR ANSWER:
356
The suggested answer is
74.16 g/mol
For polydimethylsiloxane, each mer unit consists of two carbons, six
hydrogens, one silicon, and one oxygen; thus the mer weight is
= 74.16 g/mol
11. Calculate the weight-average molecular weight (in g/mol) for a polyvinyl
chloride for which the weight-average degree of polymerization is 27,700.
YOUR ANSWER:
564
The suggested answer is
1,731,000 g/mol
The mer molecular weight for polyvinyl chloride (C2H3Cl) is equal to
Inasmuch as the weight-average degree of polymerization is defined by the
equation
The weight-average molecular weight is calculated as
12. The number-average molecular weight of a poly(styrene-methyl
methacrylate) alternating copolymer is 1,760,000 g/mol. Determine the
average number of styrene ( = 104.14 g/mol) and methyl methacrylate (
= 100.11 g/mol) mer units per molecule.
YOUR ANSWER:
746
The suggested answer is
8617
For an alternating copolymer, the number of both types of mer units will be
the same. Considering them as a single mer unit, the average number of each
mer unit is simply the number-average degree of polymerization as
where the copolymer mer molecular weight, is equal to the sum of
styrene and methyl methacrylate mer weights. The mer molecular weights
for both styrene and methyl methacrylate mers were given in the problem
statement. Therefore,
13. How do the densities of crystalline and amorphous polymers of the same
material and having identical molecular weights compare?
A. Density of crystalline polymer < Density of amorphous polymer
B. Density of crystalline polymer = Density of amorphous polymer
C. Density of crystalline polymer > Density of amorphous polymer
The density of a crystalline polymer is greater than an amorphous
polymer of the same material and having the same molecular weight.
14. For the following two polymers do the following: indicate if it is not
possible to determine if one polymer is more likely to crystallize than the
other. On the other hand, if it is possible to make such a determination
then indicate which of the two is more likely to crystallize.
Linear polyethylene
Lightly branched isotactic polypropylene
A. Lightly branched isotactic polypropylene
B. Linear polyethylene
C. Not possible
The linear polyethylene is more likely to crystallize. The mer structure for
polypropylene is chemically more complicated than is the mer structure
for polyethylene. Furthermore, branched structures are less likely to
crystallize than are linear structures.
15. Calculate the percent crystallinity (%) of a polymeric material having a density of 0.935 g/cm3
given the following information:
(a) There are the equivalent of 12 mer units associated with each unit cell.
(b) The unit cell is orthorhombic (i.e., α = β = γ = 90°), with edge lengths of 0.656, 2.172, and
0.713 nm.
(c) The mer molecular weight is 103 g/mol.
(d) The density of the totally amorphous material is 0.806 g/cm3.
YOUR ANSWER:
68
The suggested answer is
23.0%
The density of a totally crystalline polymer may be determined using the following equation:
where n is the number of mer units per unit cell, A is the mer molecular weight, VC is the unit
cell volume, and NA is Avogadro's number. Since the unit cell is orthorhombic, its volume is
given by
Thus, the density of the totally crystalline polymer may be determined as follows:
The percent crystallinity and density of a polymer specimen of density ρs are related by
where ρc and ρa are the densities for the totally crystalline and amorphous materials,
respectively. The value of ρc (2.02 g/cm3) was determined above, whereas values of ρs (0.935
g/cm3) and ρa (0.806 g/cm3) are provided in the problem. Therefore, the percent crystallinity of
this material is
= 23.0%
Retake Test