Download Chemistry 100 Second Homework

Chemistry 110 – 02
Fall 2016
Twelfth Homework
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Finish studying Hill and McCreary Chapter 10 sections 1 - 5.
Study Hill and McCreary Chapter 16 sections 2 - 5.
Prepare for the Final Exam. Check the syllabus for the day and time.
o Retake all the quizzes. Study the topics you don’t remember.
o Redo the homework. Study the topics you don’t remember.
o Don’t forget to refresh such things as formulas and names of polyatomic ions, names
of alkanes, etc.
o Study your class notes.
o Pack your calculator!
Turn in your lab notebook no later than the beginning of the final exam. You may
turn it in sooner.
This homework will not be turned in. It is to help you study for the final exam. The answer key will
be provided Thursday.
1. Draw the structure of the addition polymer formed from each of these compounds.
CH3
a. CCl2=CH2
b.
H2C
C
CH3
2. The compound tetrafluoroethylene (CF2=CF2) can be used to make the addition polymer
polytetrafluoroethylene (PTFE or Teflon ®).
a. Draw the structure of a short segment of polytetrafluoroethylene.
b. What type of intermolecular attractions are present between polytetrafluoroethylene
molecules? (Be careful! Think about the shape of the molecule.)
c. The C-F bond in polytetrafluoroethylene has a bond energy of about 504 kJ/mole. (As a
comparison, the C-C single bond has a bond energy of 376 kJ/mole.) Would you expect
polytetrafluoroethylene to be very reactive? Briefly explain your thinking.
3. a. What happens at the nanoscale when a polymer is cross-linked?
b. How do the macroscopic properties of a polymer change when it is cross-linked?
4. Draw the structure of the condensation polymer formed from this compound.
CH3 O
HO CH2 CH
C OH
5. a. Draw the structure of a carbohydrate that contains an aldehyde group.
b. Draw the structure of a carbohydrate that contains a ketone group.
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6. a. Draw the structure of a saturated fatty acid that might be commonly found in nature.
b. Draw the structure of an unsaturated fatty acid that might be commonly found in nature.
7. Oleic acid is a cis monounsaturated fatty acid with 18 carbons atoms.
a. Show the chemical reaction that occurs when an oleic acid molecule is hydrogenated.
(Remember, hydrogenation is the addition reaction in which H2 is added.)
b. How does the melting point change when oleic acid is hydrogenated?
c. Why does the melting point change this way?
8.
Each of these molecules is a fatty acid. Which are unsaturated fatty acids and which are
saturated fatty acids? (Note: the hydrogen atoms are not shown.) Explain how you arrived at
your answers.
a.
b.
c.
9. Below is the structure of a saturated triglyceride.
a. Is this molecule soluble in water or not soluble in water?
b. Show the chemical reaction that occurs when this triglyceride is hydrolyzed.
c. This reaction (the hydrolysis of the triglyceride) occurs in your small intestine. It is called
digestion. What is the name of the enzymes that allow the reaction to proceed at a fast rate?
O
H2C
O
C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH3
O CH2
HC
O
C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH
CH
CH
CH
CH
CH
CH
CH3
2
2
2
2
2
2
2
2
O
H2C
O
C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH3
10. a. Pick an amino acid (see Table 16.3 your text). Draw the structure of the amino acid you
picked.
b. Identify the amine group, the acid group, and the side chain in the amino acid you drew.
11. A dipeptide is a molecule made by attaching two amino acids via a peptide bond. Draw the two
different ways a glycine molecule and an alanine molecule can combine to form a dipeptide.
The side chain of glycine is –H and the side chain of alanine is –CH3.
12. Use Table 16.3 in your text to answer this question.
For each pair of amino acids, what type of attractions will occur between the side chains?
a. leucine and isoleucine
b. serine and asparagine
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13. Proteins have multiple levels of structure. What is the primary structure of a protein?
14. The protein lysozyme plays an important role in protecting us against bacteria. The structure
of the protein is shown here. See the online copy of the homework for a color version.
(Reference: PDB ID: 2LYZ. Diamond, R. Real-space refinement of the structure of hen
egg-white lysozyme. (1974) J.Mol.Biol. 82: 371-391,
http://www.pdb.org/pdb/explore/explore.do?structureId=2LYZ ).
a. Identify the alpha-helix and beta-pleated sheet regions.
b. What level of structure are alpha-helix and betapleated sheet (primary, secondary, tertiary,
quaternary)?
c. What type of attraction holds the molecule in an
alpha-helix or beta-pleated sheet shape?
d. Do the attractions that hold the molecule in an
alpha-helix or beta-pleated sheet shape arise from the
protein backbone or the side chains?
Lysozyme molecules are surrounded by water
molecules.
e. Where do you expect the nonpolar side chains are located in this protein and where do you
expect the polar side chains are located? Explain why.
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