Crude oil

What is crude oil?

A mixture of hydrocarbons found in the Earth's crust.

What is fractional distillation?

The process that separates crude oil into fractions based on their boiling points in a fractionating column.

Name the main fractions obtained from crude oil and their uses.

Refinery gases: bottled gas; Gasoline: fuel for cars; Kerosene: jet fuel; Diesel: fuel for lorries/trains; Fuel oil: ships/heating; Bitumen: roads.

What is the trend in colour, boiling point and viscosity in crude oil fractions?

As chain length increases: Colour darkens, Boiling point increases, Viscosity increases.

What is a fuel?

A substance that releases heat energy when burned.

What are the products of complete combustion of hydrocarbons?

Carbon dioxide (CO2) and water (H2O).

What are the products of incomplete combustion?

Carbon monoxide (CO), carbon (soot), and water (H2O).

Why is carbon monoxide poisonous?

It reduces the blood's ability to carry oxygen, leading to suffocation or death.

How are oxides of nitrogen formed in car engines?

At high temperatures, nitrogen and oxygen in the air react to form nitrogen oxides (NOx).

What forms sulfur dioxide in combustion reactions?

Combustion of hydrocarbon fuels containing sulfur impurities.

How do sulfur dioxide and nitrogen oxides cause acid rain?

They dissolve in rainwater to form sulfuric and nitric acids, lowering the pH of rain.

What is cracking?

Breaking down long-chain alkanes into shorter alkanes and alkenes.

How is catalytic cracking carried out?

Using silica or alumina as a catalyst at 600-700 degrees Celsius.

Why is cracking important?

It balances the supply of long-chain hydrocarbons with the high demand for shorter chains and alkenes.