Required practical: preparation of a soluable salt

• Method

  1. Add 50 cm3 dilute acid into a beaker and warm gently using a Bunsen burner
• method

  2.

  1. Add the insoluble oxide slowly to the hot dilute acid and stir until the base is in excess (i.e. until the base stops dissolving and a suspension of the base forms in the acid)
• Method

  3. Filter the mixture into an evaporating basin to remove the excess base
• Method 


  4.

  1. Gently heat the solution in a water bath or with an electric heater to evaporate the water and to make the solution saturated
• Method 


  5.

  1. Check the solution is saturated by dipping a cold glass rod into the solution and seeing if crystals form on the end
• Method 


  6.

  1. Leave the filtrate in a warm place to dry and crystallise
• Method 


  7. pour out excess solution and allow the crystals to dry
• Results from experiment

  Hydrated copper(II) sulfate crystals ( or other metal sulfate) should be bright blue and regularly shaped
• Conclusion of experiment

  Acid-base reactions produce salt and water with the regular shape of the salt reflecting the ionic lattice structure in its bonding
• The base is added in excess to use up all of the acid, which would become dangerously concentrated during the evaporation and crystallisation stages
• Materials:

  • 1.0 mol/dm3 dilute sulfuric acid
  • Copper(II) oxide
  • Spatula & glass rod
  • Measuring cylinder & 100 cm3 beaker
  • Bunsen burner
  • Tripod, gauze & heatproof mat
  • Filter funnel & paper, conical flask
  • Evaporating basin and dish.
• Experiment image