Fuels and Crude Oil: แบบฝึกหัด

Which of the following is a non-renewable source of energy commonly used as a feedstock for the chemical industry?

Which of the following correctly describes a difference between biofuels and fossil fuels in terms of environmental sustainability?

Which of the following statements about the fractional distillation of crude oil is incorrect?

Which of the following is a renewable alternative to crude oil and natural gas?

Fractional distillation of crude oil relies on the fact that different hydrocarbons have different physical properties. Which property is the primary basis for this separation?

State why natural gas is classified as a non-renewable resource, whereas biogas is considered renewable.

Cracking of petroleum fractions produces hydrogen as a valuable by-product. State two large-scale industrial uses of the hydrogen gas produced from cracking.

State two reasons why fractions from crude oil, such as naphtha, are highly valuable as chemical feedstocks in addition to being used as fuels.

Fractional distillation of crude oil is a process that separates the mixture into various fractions based on their boiling points.

(a) Describe why crude oil must be separated before it can be used effectively.
(b) Explain the relationship between the number of carbon atoms in a hydrocarbon molecule and its boiling point.
(c) One of the fractions obtained is naphtha. State one major use of the naphtha fraction in the chemical industry.

Crude oil is a complex mixture of hydrocarbons that must be refined before use. One of the processes involved in refining is fractional distillation, followed by cracking of heavier fractions.

(a) Explain, in terms of molecular size and intermolecular forces, why different fractions of crude oil are collected at different heights in a fractional distillation column. (2 marks)

(b) Long-chain alkanes, such as tetradecane (\(C_{14}H_{30}\)), are often cracked to meet the high demand for shorter-chain alkanes and alkenes. Write a balanced chemical equation for the cracking of one molecule of tetradecane to produce one molecule of octane and three molecules of a gaseous alkene. (1 mark)

(c) Bioethanol is considered a renewable alternative to petroleum-based fuels. Explain why the use of bioethanol as a fuel is considered more 'carbon-neutral' than using fuels derived from crude oil, even though both produce carbon dioxide upon combustion. (2 marks)

(d) State one social or economic factor that might limit the widespread adoption of biofuels over traditional fossil fuels. (1 mark)