Fuels (Cambridge (CIE) IGCSE Combined Science: Chemistry): Flashcards

A hydrocarbon is a compound made up of hydrogen and carbon atoms only. Methane, the main component of natural gas, is an example of a hydrocarbon.

The three main fossil fuels are:

1. Coal

2. Natural gas (mainly methane)

3. Petroleum (crude oil)

Fractional distillation is the process used to separate crude oil into groups of hydrocarbons called fractions according to their boiling points using a fractionating column.

In the fractionating column, fractions with high boiling points condense near the bottom, while fractions with low boiling points rise higher up.

False.

Petroleum (crude oil) is a mixture of many different hydrocarbons. The mixture must be separated by fractional distillation into useful fractions.

Longer chain hydrocarbons have higher boiling points because there are stronger attractive forces between the molecules, so more energy is needed to separate them. Shorter chain fractions have lower boiling points and collect at the top of the column.

1. Gasoline (petrol): fuel for cars

2. Diesel (gas oil): fuel for diesel engines

3. Bitumen: surfacing roads

Going from the bottom to the top of the fractionating column, chain length decreases and boiling point decreases.

False.

Refinery gas has the shortest chain length and the lowest boiling point, so it is collected near the top of the fractionating column.