FuelsIntermediate 2 Chemistry

Unit 2(a)

Fuels and combustion

• A fuel is “a substance which is burned to release energy”.

• “Combustion” is another word for “burning”.

• Burning requires oxygen (O2).

Enough fuel for 4 billion more years

Burning fuels

• When a substance burns ALL of the different types of atom in it react with oxygen

Atoms in fuel Products

CarbonCarbon dioxide,

carbon monoxide

HydrogenHydrogen oxide

(water)

Sulphur Sulphur dioxide

Equations

Write word and chemical equations for the following substances burning:

1. Methane (CH4)2. Glucose (C6H12O6)3. Hydrogen (H2)4. Ethanol (C2H5OH)5. Carbon6. *Coal (contains carbon, hydrogen and sulphur)

– no need for a chemical equation here

Hydrocarbons

A hydrocarbon is “a substance which contains hydrogen and carbon ONLY”.

Which of the following substances are hydrocarbons?

1. Methane (CH4)

2. Glucose (C6H12O6)

3. Hydrogen (H2)

4. Ethanol (C2H6O)5. Carbon

Testing for the products of combustion

Cobalt chloride paper Lime water

Types of combustion

• Look at a Bunsen burner and the different types of flame.

• There are 2 types of combustion – complete and incomplete

Complete combustion

Hydrocarbon oxygen carbon dioxide

water+ +

Incomplete combustion

Hydrocarbon oxygen carbon monoxide

water+ +

carbon+

Carbon Dioxide vs Monoxide

Chemical Formula Chemical Test Other information

Carbon dioxide CO2

Lime water turns from colourless

to cloudy

We breath it out; it makes drinks fizzy; it

dissolves in water producing a weak acid;

it is associated with “global warming”

Carbon monoxide

CO No testPoisonous gas, does

not dissolve

Cars and pollution

• Cars burn petrol (C8H18)

• Petrol sometimes contains sulphur compounds

• What products of combustion will come out of the exhaust?

Sulphur dioxide

• SO2

• Dissolves in rain water to produce acid rain

Cars and pollution 2

• Nitrogen monoxide and nitrogen dioxide also come out the exhausts of cars

• They also cause acid rain

• Where do they come from?

Nitrogen and Oxygen

• A high-energy spark from the engine spark plug allows N2 and O2 to react.

• Oxides of nitrogen (NO, NO2 etc) are produced.

N N O O

N2 O2

Alternative Fuels