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GCSE Chemistry · key term
A mixture of hydrocarbons collected from crude oil that have similar boiling points.
Used by AQA, Edexcel and OCR
Specification 4.7.1.2 · Paper 2
A group of hydrocarbons from crude oil whose molecules have similar numbers of carbon atoms and similar boiling points.
Revise: Fractional DistillationThe mixture is more useful when it is separated into fractions. Each fraction still contains a mixture, but its molecules have similar numbers of carbon atoms and similar boiling points. This makes each fraction suitable for particular uses.
Specification 8.3, 8.4, 8.5 · Paper 2
A simpler mixture collected over a range of boiling points; in crude oil, it contains hydrocarbons with similar chain lengths and properties.
Revise: Fractional DistillationCrude oil is therefore much more useful after it has been separated into fractions: simpler mixtures whose hydrocarbons have similar boiling points, chain lengths and properties.
A mixture of hydrocarbons with similar boiling points, separated from crude oil.
A mixture of hydrocarbons with a similar range of boiling points, separated from crude oil by fractional distillation.
A mixture of substances collected over a range of boiling temperatures.
Specification C6.2j, C6.2k, C6.2l · Paper 2 (Foundation), Paper 4 (Higher)
Revise: Crude Oil SeparationCrude oil is not one substance. It is a mixture of many hydrocarbons, which are compounds made only of carbon and hydrogen. These hydrocarbons have different boiling points, so they can be separated into useful groups called fractions.
A group of substances collected from a mixture whose components have a similar range of boiling points.
A group of compounds collected from crude oil whose molecules have similar boiling points.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A mixture of hydrocarbons with similar-sized molecules and a narrow range of boiling points.
Revise: Fractional distillationBecause crude oil is a mixture, these hydrocarbons must be separated into more useful groups called fractions. The molecules in a fraction are similar in size and have a narrow range of boiling points; a fraction is not one pure substance.
A mixture of hydrocarbons collected together because its components have a similar range of boiling points.
A fraction is a mixture of hydrocarbons with similar numbers of carbon atoms, not a single pure compound.
Distillation separates substances; further processing can turn fractions into fuels or petrochemical feedstock. AQA does not require names of other specific fractions or fuels beyond those stated in the specification.
Do not say that each fraction is a single hydrocarbon. Each fraction is a simpler mixture of hydrocarbons with similar boiling points.
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