Required Practicals

• Salt


  A compound containing a positive ion (metal ion) and a negative ion (from an acid)
• Sources of metal ions for salts

  • Metal
  • Metal oxide
  • Metal hydroxide
  • Metal carbonate
• Negative ion in a salt

  Comes from the acid
• Making a soluble salt using an acid


  1. Use dilute acid as limiting reactant

  2. Heat acid to almost boiling

  3. Add small amounts of metal oxide and stir

  4. Stop adding oxide when solution is blue

  5. Filter to remove unreacted oxide

  6. Evaporate solution to form crystals

  7. Allow crystals to form over 24 hours

  8. Dry the crystals
• Cannot make copper sulfate by reacting copper metal with dilute sulfuric acid, as copper is not reactive enough
• The steps described would also apply to making a salt using a metal carbonate
• The solution needs to be neutral at the end, with no excess acid remaining
• Filtering removes the unreacted insoluble metal oxide
• Evaporation is used to form the salt crystals
• Crystals are dried on a paper towel