Chemistry C3.2 (Water)

Mindmap of the 2013 AQA GCSE Chemistry C3 Water unit.  Includes; Hard Water, Removing Hardness, Water Treatment & Water Issues.

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  • Created by: Ethan
  • Created on: 21-03-13 20:16
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  • Chemistry C3 U2 (Water)
    • Hard Water
      • Needs more soap to create a lather and wash effectively
        • Soapless detergents do not react with hard water to form scum
          • Salts in hard water react with soap to form an insoluble solid called scum
            • Needs more soap to create a lather and wash effectively
              • Soapless detergents do not react with hard water to form scum
                • Salts in hard water react with soap to form an insoluble solid called scum
        • Contains dissolved Calcium (Ca) and Magnesium (Mg) salts
          • When water is in contact with rocks some compounds dissolve
            • Contains dissolved Calcium (Ca) and Magnesium (Mg) salts
            • When temporary hard water is heated it produces an insoluble solid, scale
              • Scale deposits build up
                • Reduces efficiency of heating systems
                • Can also cause blockages in pipes
            • Dissolved Calcium (Ca) ions are good for health
              • Helping develop strong bones + teeth
              • May also reduce the risk of heart disease
          • Removing Hardness
            • Soft water may contain dissolved substances, but these do not produce scale or scum
            • Temporary hard water is made soft by boiling
              • When temporary hard water is heated it produces an insoluble solid, scale
                • Scale deposits build up
                  • Reduces efficiency of heating systems
                  • Can also cause blockages in pipes
              • Temporary Hard water contains Hydrocarbonate ions (HCO3-)
                • When heated these decompose into in carbonate ions, water and CO2
                  • The carbonate ions react with Mg and Ca ions in the water to produce participates
                    • Calcium Carbonate & Magnesium Carbonate
              • Adding Sodium Carbonate (washing soda)
                • It reacts with the Ca and Mg ions in the water to form participates
                  • Participates are solid Calcium Carbonate & Magnesium Carbonate
              • Ion-exchange columns with resin in containing Sodium or Hydrogen Ions
                • Water passes through the resin
                  • Ca and Mg ions become attached to the resin, and the Na or H ions take there place in the water
                    • Na or H ions do not react with soap
                      • Ion-exchange columns with resin in containing Sodium or Hydrogen Ions
                        • Water passes through the resin
                          • Ca and Mg ions become attached to the resin, and the Na or H ions take there place in the water
                            • Na or H ions do not react with soap
                              • However Na ions can be bad for health
                      • However Na ions can be bad for health
            • Water Treatment
              • Water  is gathered from an appropriate source (lake, river, sea)
                • Treated by Sedimentation
                  • Goes through Filtration
                    • Is then disinfected  (Chlorinated)
                      • To kill any microbes in the water
                    • Normally through sand, removes other substances
                  • Uses gravity to remove suspended solids from still water
              • Pure water can be made by distilation
                • However there is a large amount of energy used to boil the water
                  • So this is to expensive to do on a large scale
              • Water filters can be used to improve taste of water
                • Contain Carbon and ion-exchange resin
                  • Remove some soluble substances + silver to prevent growth of bacteria
            • Water Issues
              • Chlorine
                • Very effective at killing microbes
                • Poisonous and can produce other toxic compounds
              • Flouridation
                • 30% reduction in teeth cavities
              • Hard/Soft Water
                • Hard Water
                  • When water is in contact with rocks some compounds dissolve
                    • Dissolved Calcium (Ca) ions are good for health
                      • Helping develop strong bones + teeth
                      • May also reduce the risk of heart disease

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