8 – Hydrocarbons

Leaving Certificate Chemistry

Organic Chemistry

Leaving Certificate Chemistry

Fuels• Fuels are things which burn in oxygen to

produce heat energy.

Fossil fuels

They are non-renewable

Formation of Hydrocarbons

When plants die in anaerobic conditions, they become fossilised and hydrocarbons are eventually formed over time

Definition

• A hydrocarbon is a compound which contains carbon and hydrogen atoms only

Fossil fuels

Coal formation

Oil and gas formation

Fossil Fuels are Hydrocarbons

OIL

COAL

NATURAL GAS

These are all excellent sources of energy.

They are superb fuels.

Methane – An Important Hydrocarbon

C

H

H

H

H

Methane

Why is Methane useful as a Fuel?

It has a very high kilogram calorific value. It is easily

distributed in pipes

It is a relatively clean fuel

2004 – Higher Level – Q.6 (c) (6)

Sources of Methane

Decomposition of animal and vegetable waste – For example in swamps

From Cows…..

From Landfill Sites

2002 – Higher Level – Q.8 (b) (3)

Hazards of Methane• It is a colourless, odourless gas

which when ignited produces explosions.

• However smelly chemicals called mercaptans are deliberately placed into natural gas supplies so we can detect leaks.

2002 – Higher Level – Q.8 (b) (3)

2004 – Higher Level – Q.6 (b) (3)

Methane & The Greenhouse Effect

Methane is a greenhouse gas and so it enhances the greenhouse effect which leads to global warming.

2002 – Higher Level – Q.8 (b) (3)

Check your learning..

• What is a hydrocarbon?

• What is a fuel?

• What is a fossil fuel and examples?

• About methane – sources, why good fuels, hazards?