Making salts

• What is the aim of the experiment described in the study material?

  Preparation of a pure, dry sample of a soluble salt from an insoluble oxide or carbonate
• What equipment is needed for the preparation of a pure dry salt?

  • 1.0 M dilute sulfuric acid
  • Copper (II) oxide powder
  • A spatula
  • A glass rod
  • A measuring cylinder
  • Two beakers (100 cm³ and 250 cm³)
  • Bunsen burner
  • Tripod
  • Gauze
  • Heatproof mat
  • Filter funnel and paper
  • A small conical flask
  • An evaporating basin
  • A crystallising dish
• How much sulfuric acid should be measured for the experiment?


  20 cm³
• What is the first step in the method for preparing the salt?

  Measure 20 cm³ sulfuric acid into a measuring cylinder and pour it into a beaker
• What should be done after measuring the sulfuric acid?


  Heat the acid gently using a Bunsen burner
• What is added to the sulfuric acid during the experiment?


  Small amounts of insoluble base, specifically copper oxide
• How do you know when to stop adding copper oxide to the sulfuric acid?


  When no more reacts and no more effervescence is produced
• What is the purpose of filtering the solution?

  To remove the excess copper oxide
• What should be done with the solution after filtering?


  Pour the solution into the evaporating basin
• How is the solution evaporated?


  Using a water bath until crystals start to form
• How long should the evaporating basin be left in a cool place?


  At least 24 hours
• What is the final step in the preparation of the salt?

  Gently pat the crystals dry between two pieces of filter paper
• What safety precautions should be taken during the experiment?

  • Wear safety goggles as sulfuric acid is corrosive
  • Tie back hair
  • Turn off the Bunsen burner when not in use or leave it on the orange safety flame
• Why should safety goggles be worn during the experiment?

  Because sulfuric acid is corrosive
• What should be done with hair during the experiment?


  Make sure hair is tied back
• What should be done with the Bunsen burner when not in use?


  Turn it off or leave it on the orange safety flame