Contents
Key Stage 3
Meaning
A base is a metal compound with a pH greater than 7.
About Bases
- A base can be Harmful, Irritant or corrosive.
- Bases can neutralise an acid.
- Many bases are insoluble solids.
- A base can be a:
- Metal Hydroxides are soluble bases known as 'Alkalis'.
Examples
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| Drain cleaner is around pH 14. | Oven cleaner is around pH 13.5. | Toilet cleaner is around pH 12. |
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| Baking soda is around pH 9.5. | Sea water is around pH 8. | Blood is around pH 7.4. |
Key Stage 4
Meaning
A base is a compound which is able to produce OH- ions when dissolved in water to form a solution with a pH greater than 7.
About Bases
- Bases are ionic compounds where there is an ionic bond between a metal and an Oxide, Carbonate or Hydroxide.
- Bases will react with acids to form a salt.
- Some bases are insoluble.
- A soluble base will dissolves in water to produce an alkali which has Hydroxide ions which are either donated by the base or formed by a reaction with water to form a Hydroxide ion.
- The Hydroxide ions in an alkali will donate electrons to Hydrogen ions to form water. This is a neutralisation reaction.
Extra Information
References
AQA
- Bases, page 204, GCSE Biology; Third Edition, Oxford University Press, AQA
- Bases, page 246, GCSE Biology, CGP, AQA
- Bases, page 247, GCSE Combined Science Trilogy 1, Hodder, AQA
- Bases, page 280, GCSE Chemistry, Hodder, AQA
- Bases, pages 128, 129, GCSE Combined Science; The Revision Guide, CGP, AQA
- Bases, pages 130-132, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
- Bases, pages 155-157, GCSE Chemistry, CGP, AQA
- Bases, pages 51, 54, GCSE Chemistry; The Revision Guide, CGP, AQA
- Bases, pages 92-93, 96-97, 163, GCSE Chemistry; Third Edition, Oxford University Press, AQA