practicals

• Indicators


  Used to determine whether a solution is acidic or alkaline
• Neutralisation


  Reaction between an acid and a base
• Acids


  • React with metals, bases and carbonates to produce salts
• Soluble salt


  Able to dissolve in solvent
• Insoluble oxide or carbonate


  Unable to dissolve in a particular solvent
• Preparation of a pure, dry sample of a soluble salt from an insoluble oxide or carbonate

  1. Use appropriate heating devices safely

  2. Use appropriate apparatus and techniques, including a suitable choice of reactants

  3. Safely use equipment to purify or separate mixtures by filtration

  4. Handle substances carefully, and mix them safely
• Eye protection must be worn throughout the practical
• Steps in the practical

  1. Add powdered insoluble reactant to acid in a beaker, one spatula at a time, stirring to mix

  2. Continue adding powder until it is in excess (some unreacted powder is left over)

  3. Filter the mixture in the beaker to remove the excess powder

  4. Collect the filtrate

  5. Pour the filtrate into an evaporating basin

  6. Place on a water bath, and heat until about half the water from the solution has been removed by evaporation

  7. Stop heating when small crystals start to appear around the edge of the evaporating basin

  8. Pour the remaining solution into a watch glass, and leave in a warm, dry place for crystallisation to occur

  9. If necessary, dry the crystals by dabbing gently with filter paper
• Evaluation of the practical

  • Were good quality crystals obtained? If so, why?
  • What improvements could be made to the method?
  • Was the practical carried out safely? What improvements could be made?