Salt Preparation Including Titration Calculations

• Acids

  React with metals, bases and carbonates to form salts
• Preparation of salt crystals from acids

  Depends on whether the substances they are reacting with are soluble or insoluble
• Preparation of a salt from a metal or insoluble base/carbonate


  • Metals, bases and certain metal carbonates are insoluble in water
  • There are three stages in the preparation
• Stage 1 of salt preparation from metal/base/carbonate

  1. Excess metal/base/carbonate is added to the acid to make sure all the acid has reacted and been used up

  2. Heating and stirring help the process

  3. For metals and metal carbonates, the fizzing stops when all the acid has been used up
• Stage 2 of salt preparation from metal/base/carbonate

  1. The mixture is filtered using a filter funnel and filter paper

  2. The excess solid remains in the filter paper

  3. The salt solution passes through into the evaporating basin
• Stage 3 of salt preparation from metal/base/carbonate

  1. The salt crystals are collected from the solution by evaporation

  2. The solution is heated to evaporate the water

  3. Large crystals - evaporate water slowly near a radiator or window ledge

  4. Small crystals - use a Bunsen to evaporate 2/3 of the water quickly, before allowing to crystallise naturally
• Alkali


  A soluble base
• Preparation of a salt from an alkali or soluble carbonate


  A titration is used to produce a salt from an acid and alkali
• Titration method to produce a salt from an acid and alkali

  1. Measure exactly 25 cm3 of alkali into a clean conical flask

  2. Add a few drops of indicator to the flask

  3. Place the flask onto a white tile

  4. Fill the burette with acid

  5. Slowly add the acid from the burette to the alkali until the indicator changes colour

  6. Record the volume of acid added to the flask

  7. Repeat steps 1-6 without using the indicator and adding the same volume of acid from the burette
• Insoluble salt


  Made when solutions of two soluble salts react in a precipitation reaction
• Preparation of insoluble salts

  1. Mixing - The two soluble salt solutions are mixed

  2. Filtration - The insoluble precipitate is separated from the mixture by filtration

  3. Washing and drying - Water cannot dissolve the precipitate - it is insoluble - but it can wash off any remaining impurities. The filter paper is then removed, opened out and the precipitate dried in an oven
• Concentration

  The number of moles per dm3
• Titration calculation 1:1 mole ratio

  1. Convert all volumes to dm3

  2. Calculate the number of moles of the substance where the volume and concentration are known

  3. Calculate the unknown concentration
• Titration calculation 2:1 mole ratio


  1. Convert all volumes to dm3

  2. Calculate the number of moles of the substance where the volume and concentration are known

  3. Calculate the unknown concentration