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Salts

Science Practicals: GCSE, topic 2.1.1

Soluble Salts

Soluble salts are salts which dissolve in water.

Making soluble salts

Making soluble salts

  • Soluble salts can be made by reacting acids with solid, insoluble substances such as pure metals, metal oxides, metal hydroxides, or metal carbonates.
E.g. blue copper sulfate

E.g. blue copper sulfate

  • Blue copper sulfate crystals are produced by adding black copper oxide to sulfuric acid:
  • CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)

Required Practical - Separating Mixtures

The aim of this practical is to produce a pure, dry sample of a soluble salt from an insoluble oxide or carbonate.

Preparation

Preparation

  1. ­­Gently warm an acid using a Bunsen burner,
  2. Add the insoluble solid (with stirring) until no more reacts.
Filtration

Filtration

  1. Filter the solution to remove the excess insoluble solid.
  • This will leave a solution of the salt dissolved in water.
Crystallisation

Crystallisation

  1. Heat the solution in an evaporating basin above a beaker of water.
  • The 'water bath' ensures gentle heating.
  1. Leave the solution to cool and allow more water to evaporate.
  • As water evaporates, the solution will become more concentrated and the salt will begin to crystallise.

Test yourself on Salts

  • What do we call salts that dissolve in water?

  • What must be reacted together to produce a soluble salt?

Practise this topic for free