April 24, 1997

There are three pages and twelve questions on this exam. Be sure you have them all.

1. Describe or define precisely and give an example of each

Conformer (2 points)

Cis and trans isomers (2 points)

Structural isomers (2 points)

Cracking of alkanes (2 points)

Combustion of an alkane (2 points)

Serial titration (2 points)

2. Draw the following molecule, describing clearly the bond angles around the carbon atom marked with the *, and circling all the atoms which necessarily lie in the same plane as that carbon atom.

CH₃CH=C(CH₃)CH₂CH₃

               *

(6 points)

 3. Draw structures of each of the following:

2-methyl-1-pentene 3,3-dimethylhexane 1-chloro-4-ethyloctane

(9 points)

 4. Circle each of the following molecules which can have cis and trans isomers:

            hexane          1-hexene          2-hexene          3-hexene

(8 points)

5. How many different isomers of the molecule C₄H₉Cl can exist? Draw each of them.

 (10 points)

6. Name each of the following using IUPAC nomenclature:

CH₃CH₂CH₂CH(CH₃)CH(C₂H₅)CH₂CH₃ CH₃CH₂CH=C(CH₃)CH₃

(10 points) 

7. Write the chemical (molecular) formula of each of the following. (in the original, several structural drawings were presented)

(10 points)

 8. Rank in increasing order the expected boiling points of

CH₃CH(CH₃)₂CH₂CH₃ CH₃CH₂CH₃ CH₃(CH₂)₆CH₃

(5 points)

9. What substances are represented by each of the following carbon-atom structures?

(5 points)

10. The following questions refer to the Vitamin-C laboratory experiment. Show all your work and circle your answers.

(a) During standardization of the DCP, 2 drops of 0.50 mg/mL vitamin-C standard requires 7 drops of DCP to reach the endpoint, while 2 drops of an unknown vitamin-C solution requires 5 drops of DCP. What is the concentration of vitamin-C, in mg/mL, in the unknown?

(5 points)

 (b.) A whole lemon is squeezed, yielding 25 mL of juice. If 2 drops of juice require 5 drops of the same standardized DCP, how many mg of vitamin-C are in the whole lemon?

 (5 points)

 11. (a.) Shown below is the monomer unit methyl methacrylate. Draw the structure of polymethacrylate that would result from polymerizing this monomer (show several repeating sections of the polymer).

 (5 points)

(b.) Describe why polymers such as polymethacrylate (Lucite) have the useful physical properties that they do.

 (5 points)

 12. Account for the observation that Br₂ reacts readily at room temperature with one of the following, whereas the other has no such effect. Describe the reaction that occurs in the one case, and explain why no reaction occurs in the other case, even though the reactants appear to be similar.

 (5 points)