C4.2.3 - Soluble Salts

• Soluble salts can be prepared by reacting an acid with an insoluble base (usually a metal oxide or metal hydroxide).

  • Heat the acid in a water bath to speed up the rate of reaction.
  • Once the acid is warm, add the insoluble base. Add the solid base bit by bit, until there is an excess of unreacted solid left over
  • The acid and base will have reacted to produce a soluble salt and water. Filter to remove the excess unreacted base to leave a solution containing only the salt and water.
  • Evaporate off the water by gently heating the solution. Allow to cool and the soluble salt will crystallise.

  
• Soluble salt reactions

  Metal + Acid -> Salt + Hydrogen

  Metal Hydroxide (Alkali) + Acid -> Salt + Water

  Metal Oxide + Acid -> Salt + Water

  Metal Carbonate + Acid -> Salt + Carbon Dioxide + Hydrogen