Crude oil, alkanes, alkenes and alcohols

What is a hydrocarbon?

A compound of hydrogen and carbon only

What does homologous mean?

family of organic compounds with the same functional group and general formula

What does isomerism mean

molecules that have the same molecular formula but a different structural formula

What is the prefix in a hydrocarbon?

1 carbon- methane

2 carbon- ethane

3 carbon - propane

4 carbon - butane

5 carbon- pentane

6 carbon - hexane

What is a crude oil?

A mixture of hydrocarbons

Describe how crude oil is separated in fractional distillation

Crude oil is heated in a furnace until it turns into gas

Hot vapour is fed into bottom of fractionating column which has temperature gradient (hot at bottom, cool at top)

The vapours rise up and the column and cool down

Vapours rise, different hydrocarbons condense at different height when they reach temperature = boiling point

Describe the boiling points of longer chain and shorter chain hydrocarbons

Longer chain hydrocarbons- larger molecules + stronger intermolecular forces- condense near bottom of column

Describe the names and uses of the main fractions obtained in cruel order from lowest boiling point to highest boiling point

Refinery gases- used for domestic heating and cooking

Gasoline- used as fuel for cars

Kerosene- used as fuel for aircraft

Diesel- used as fuel for cars, buses and trains

Fuel oil- used as fuel for large ships and power stations

Bitumen- used for surfacing roads and roofs

Describe the trend of boiling point, viscosity and colour of hydrocarbon molecules from top to bottom

Boiling point: increases

Viscosity: increases

Colour: darkens

What is viscosity?

How thick a liquid is and how it flows

What is fuel?

A substance that releases heat energy when burned

Describe the products of complete and incomplete combustion of hydrocarbons

Complete combustion: carbon dioxide and water

Incomplete combustion: water and carbon (monoxide)

Why is carbon monoxide poisonous?

Reduces the capacity of the blood to transport oxygen around the body

What happens at high temperatures in car engines?

The high temperature of the combustion provided enough energy for normally unreactive nitrogen and oxygen from the air to react together - forming oxides of nitrogen

Why does the combustion of sulfur impurities in hydrocarbon fuels produces sulfur dioxide

Because sulfur reacts with oxygen from air at high temperature