Chapter 21

The general formula for alkanes is \(\mathrm{C}_{n} \mathrm{H}_{2 n+2} .\) Determine the general formula for cycloalkanes.

Manufacturing Why are unsaturated hydrocarbons more useful than saturated hydrocarbons as starting materials in chemical manufacturing?

Is cyclopentane an isomer of pentane? Explain your answer.

Why do chemists use structural formulas for organic compounds rather than molecular formulas such as \(\mathrm{C}_{5} \mathrm{H}_{12} ?\)

Which would you expect to have more similar physical properties, a pair of structural isomers or a pair of stereoisomers? Explain your reasoning.

Explain why numbers are needed in the IUPAC names of many unbranched alkenes and alkynes but not in the names of unbranched alkanes.

A compound with two double bonds is called a diene. The name of the structure shown is 1,4-pentadiene. Apply your knowledge of IUPAC nomenclature to draw the structure of 1,3-penadiene. $$\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}$$

Determine which two of the following names cannot be correct, and draw the structures of the molecules. a. 2-ethyl-2-butene \(\quad\) c. 1,5-dimethylbenzene b. 1,4-dimethylcyclohexene

Infer The sugar glucose is sometimes called dextrose because a solution of glucose is known to be dextrorotatory. Analyze the word dextrorotatory, and suggest what the word means.

Recognize Cause and Effect Explain why alkanes, such as hexane and cyclohexane, are effective at dissolving grease, whereas water is not.

Chiral Carbons Many organic compounds have more than one chiral carbon. For each chiral carbon in a compound, a pair of stereoisomers can exist. The total number of possible isomers for the compound is equal to \(2^{n}\) , where \(n\) is the number of chiral carbons. Draw each structure, and determine how many stereoisomers are possible for each compound named below. a. 3,5-dimethylnonane b. 3,7-dimethyl- 5- ethyldecane

What element has the following ground-state electron configuration: \([\operatorname{Ar}] 4 s^{2} 3 \mathrm{d}^{6} ?\) (Chapter 5)

What is the charge of an ion formed from the following families? (Chapter 7) a. alkali metals b. alkaline earth metals c. halogens

Write the chemical equations for the complete combustion of ethane, ethene, and ethyne into carbon dioxide and water. (Chapter 9)

Gasoline For many years, a principal antiknock ingredient in gasoline was the compound tetraethyl-lead. Research to learn about the structure of this compound, the history of its development and use, and why its use was discontinued in the United States. Find out if it is still used as a gasoline additive elsewhere in the world.

Perfume The musk used in perfumes and colognes contains many chemical compounds, including large cycloalkanes. Research and write a short report about the sources used for natural and synthetic musk compounds in these consumer products.