Hardness Of Water

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Soft Water:

  • Lathers well with soap

Hard Water:

  • Scum forms unless a soapless detergent is used
  • Dissolved calcium and magnesium ions react with soap to form scum (insoluble)
  • More soap required to form a lather -> more expensive
  • Forms scale when heated (Calcium Carbonate) on the insides of pipes/kettles/etc. 
    • Badly scaled boilers and pipes mean less efficient heating systems
    • Need replacing so scale doesn't block pipes -> costs money
    • Scale is a thermal insulator -> Kettle takes longer to boil so is less efficient. 

Cause of Hard Water:

  • Contain Ca2+ and Mg2+ ions
  • When rain falls on rocks like limestone, chalk and gypsum, compounds like Magnesium sulfate and


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