Hydrocarbons：練習問題

Which of the following is the correct general formula for the homologous series of alkanes?

When long-chain hydrocarbons are cracked, they are broken down into smaller, more useful molecules such as alkanes and alkenes. Which of the following is the correct general formula for the homologous series of alkenes produced during this process?

A sample of icosane (\(C_{20}H_{42}\)) is cracked to produce exactly one molecule of octane (\(C_8H_{18}\)), three molecules of ethene (\(C_2H_4\)), and one molecule of an unknown alkene, W. Which of the following identifies the molecular formula of W and correctly describes how the physical properties of octane compare to icosane?

When a hydrocarbon undergoes incomplete combustion, it can produce a toxic gas that reduces the capacity of blood to carry oxygen. Which of the following equations correctly represents the incomplete combustion of propane, \( C_3H_8 \)?

When a large hydrocarbon molecule is broken down by the process of cracking, a mixture of products is formed. If a molecule with the formula \( C_{10}H_{22} \) is cracked to produce one molecule of octane (\( C_{8}H_{18} \)), what is the formula of the other product formed, and to which homologous series does it belong?

Explain how the high temperatures within a car engine lead to the formation of oxides of nitrogen from the atmosphere and describe one major environmental problem caused by these gases.

Crude oil is a complex mixture of hydrocarbons that can be separated and processed to produce useful fuels and chemicals.

(a) Describe the process of fractional distillation used to separate crude oil into different fractions.

(b) Long-chain alkanes are often broken down into smaller, more useful molecules.
(i) Name this process.
(ii) A hydrocarbon molecule with the formula \( C_{14}H_{30} \) is broken down to produce one molecule of ethene (\( C_{2}H_{4} \)) and one other hydrocarbon molecule. Write the chemical formula for the other molecule produced.

(c) Explain why alkenes, such as ethene, are described as unsaturated hydrocarbons.