Homework Chapter 20


Homework 20.1

1. What makes carbon an important element in the study of chemistry?

2. What type of hybrid orbital is found in carbon double bonds? In carbon triple bonds?

3. How does the structure of graphite relate to its properties and uses?

4. Name and describe the structures of three allotropic forms of carbon.

5. What properties of diamond determine most of its industrial uses?

6. Why does graphite conduct electricity while diamond does not?

7. Explain why the structure of graphite makes it useful as a lubricant.

Homework 20.2

1. What are three characteristics of carbon that contribute to the diversity of organic compounds?

2. Define the term isomer, and distinguish between structural and geometric isomers.

3. Which of the following types of molecular representations can be used to show differences between isomers? Explain why each can or cannot.
a) molecular formula
b) structural formula
c) three-dimensional drawing or model

4. Write the formula for methylpropane (shown at the right on page 631) in a horizontal row.

5. Which of the following can represent the same molecule?


6. a) What is catenation?
b) How does catenation contribute ot the diversity of organic compounds?

7. What are hydrocarbons, and what is their importance?

8. a) What information about a compound is provided by a structural formula?
b) How are structural formulas used in organic chemistry?

9. Can molecules with the molecular formulas C4H10 and C4H10O be structural isomers of one another? Why or why not?

10. Can molecules with only single bonds (and no rings) have geometric isomers? Why or why not?


Homework 20.3

1. What is the basic structural characteristic of alkanes?

2. Draw all of the condensed structural formulae that can represent C5H12.

3. Give the systematic name for each of the compounds whose formulas appear in question 2.

4. Draw the condensed structural formulae of 3,4-dimethylhexane and 1-methyl-3-propylcyclopentane.

5. Give the general formula for the members of the alkane series.

6. Give the molecular formula for the alkane that contains seven carbon atoms.

7. a) What ia a homologous series?
b) By what method are straight chain hydrocarbons named?
c) Name the straight chain alkane with the molecular formula C10H22.

8. What are cycloalkanes?

9. a) What trend occurs in the boiling points of alkanes?
b) How would you explain this trend?
c) How is the trend in alkane boiling points used in petroleum fractional distillation?

Homework 20.4

1. List the basic structural features that characterize each of the following:
a) alkenes
b) alkynes
c) aromatic hydrocarbons

2. Draw three condensed structural formulae that can represent C4H8.

3. Give the systematic name for each compound in the answer to question 2 above.

4. Draw the condensed structural formula for each of the following:
a) 1,3-butadiene
b) 2-pentyne
c) 1,2-diethybenzene

5. What do the terms saturated and unsaturated mean when applied to hydrocarbons?

6. Classify the following as saturated or unsaturated:
a) alkenes
b) alkanes
c) alkynes
d) aromatic hydrocarbons

7. Give the general formula for the members of
a) alkene series
b) alkyne series

8. Give the molecular formula for each type of hydrocarbon if it contains seven carbon atoms:
a) alkene
c) alkyne

9. Draw the condensed structural formula for the following:


10. Identify each o the following pairs of formulae as representing the same or different molecules:



11. Identify whether each pair represents the same molecule or structural isomers:



12. Draw the structural formulas for the five isomers of C6H14.

13. a) Which of the following can have geometric isomers?


b) Draw the geometric isomers for those that can have geometric isomers.
c) Label each geometric isomer as cis or trans.