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WalesChemistry

Unit 2: Crude Oil and Organic Chemistry

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What are alcohols, and how is ethanol made and used?

Alcohols as a homologous series, the functional group, and the production of ethanol by fermentation and by hydration of ethene.
A focused answer to WJEC GCSE Chemistry topic 2.5 on alcohols, covering the alcohol homologous series and the -OH functional group, the uses of ethanol, and how ethanol is produced by fermentation of sugars and by the hydration of ethene.
9 min answer →

How do alkanes and alkenes differ, and why do we crack large hydrocarbons?

Alkanes and alkenes as homologous series, the test for unsaturation, combustion of hydrocarbons, and cracking to make smaller alkanes and alkenes.
A focused answer to WJEC GCSE Chemistry topic 2.5 on alkanes and alkenes, covering their general formulae, the bromine water test for alkenes, complete and incomplete combustion, and how cracking converts large hydrocarbons into smaller alkanes and useful alkenes.
10 min answer →

What is crude oil, and how is it separated into useful fuels?

Crude oil as a mixture of hydrocarbons, separation by fractional distillation, and the properties and uses of the fractions.
A focused answer to WJEC GCSE Chemistry topic 2.5 on crude oil, covering crude oil as a finite mixture of hydrocarbons, how fractional distillation separates it by boiling point, and how the properties of the fractions change down the column.
9 min answer →

How are plastics made from alkenes, and why are they hard to dispose of?

Addition polymerisation of alkenes, drawing the repeat unit, the uses of common polymers, and the problems of polymer waste and disposal.
A focused answer to WJEC GCSE Chemistry topic 2.5 on polymers, covering how alkene monomers join by addition polymerisation, how to draw the repeat unit, the uses of common plastics, and the environmental problems of polymer waste and its disposal.
9 min answer →