1. W Richards The Weald School
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Using Chemistry
W Richards
The Weald School

2. Fuels
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A “fuel” is something that can be burned to release heat and light energy. The main examples are:
Although these fuels look different, they all contain CARBON and HYDROGEN

3. Burning Fuels Lots of oxygen: Some oxygen: Little oxygen: Methane
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Lots of oxygen:
Methane
Oxygen +
Carbon dioxide
Water +
Water + O H
Methane C H
Oxygen + O C O
Some oxygen:
Carbon monoxide O H
Water + C H
Methane
Little oxygen: O
Oxygen + C
Carbon

4. Burning Hydrogen Recall the test for hydrogen: The reaction:
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Recall the test for hydrogen:
“POP”
The reaction: O H
Notice that no carbon dioxide or carbon monoxide is produced! H O
Hydrogen
Oxygen +
Water

5. Energy from Displacement Reactions
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Increasing reactivity
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Lead
Copper
Silver
Gold
In previous work we considered the reactivity series:
We also looked at displacement reactions, where a more reactive metal will displace a less reactive one from one of its compounds.

6. Energy from Displacement Reactions
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Lots of energy
Example 1 – Magnesium and copper sulphate O Cu S
Copper sulphate + Mg O S
Magnesium sulphate + Cu
Copper Mg
Magnesium
Some energy
Example 2 – Zinc and copper sulphate Zn O Cu S
Zinc +
Copper sulphate
Copper
Zinc sulphate

7. Electrical energy from differences in reactivity
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Zinc rod
Copper rod
Filter paper soaked in potassium nitrate V
Zinc sulphate
Copper sulphate
The bigger the difference in reactivity, the bigger the voltage

8. Conservation of mass in reactions
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In any reaction the total mass of products is the same as the total mass of the reactants
Example 1 – Magnesium oxide and hydrochloric acid Mg O H Cl
1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms
Also 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms
Example 2 – Burning methane C H O