Resource 5: Making Salts

Making salts

Salts are very useful chemicals. Here are some that you and your students might have come across:

• sodium chloride – table salt used for flavouring food
• ammonium nitrate – fertiliser that provides nitrogen
• calcium sulfate – plaster of Paris
• magnesium sulfate – Epsom salts, a laxative
• iron II sulfate – used in iron tablets (to treat anaemia)
• monosodium glutamate – food additive
• potassium nitrate – used in explosives
• copper sulfate – used in agriculture as a fungicide
• calcium citrate – food additive (preservative).

Making a salt from an acid and a carbonate

Here are the steps for the experiment in the correct order:

1. Measure 25 ml of 0.5 M sulphuric acid or hydrochloric acid into a beaker
2. Use a teaspoon or spatula to add copper carbonate. Stir after each addition.
3. Add the solid until the fizzing stops
4. Filter the mixture to remove unreacted copper carbonate (or decant the liquid into an evaporating basin).
5. Heat the solution until crystals just begin to appear.
6. Leave the solution to cool.
7. Pour off the liquid and dry the crystals between pieces of filter paper (or tissue paper).