Resource 5: Making Salts
Background information / subject knowledge for teacher
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:
- Measure 25 ml of 0.5 M sulphuric acid or hydrochloric acid into a beaker
- Use a teaspoon or spatula to add copper carbonate. Stir after each addition.
- Add the solid until the fizzing stops
- Filter the mixture to remove unreacted copper carbonate (or decant the liquid into an evaporating basin).
- Heat the solution until crystals just begin to appear.
- Leave the solution to cool.
- Pour off the liquid and dry the crystals between pieces of filter paper (or tissue paper).