Hardness of Water-C6
- Created by: Shannon
- Created on: 29-05-13 13:18
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- Hardness of Water
- Calcium hydrogencarb-onate dissolves to form temporary water hardness
- Calcium carbonate+ carbon dioxide ---> calcium hydrogencarb-onate
- Permanent hardness-calcium sulphate rock dissolves
- Not affected by heating
- Ion exchange resin-water flows over solid resin-trap calcium ions and exchange them for sodium ions
- CaSO4+ NaCO3 ---> Na2SO4+ CaCO3
- Ion exchange resin-water flows over solid resin-trap calcium ions and exchange them for sodium ions
- Not affected by heating
- Thermal decompostio-n softens temporary hardness
- Ca(HCO3)2 ---> CaCO3+CO2+H2O
- Washing soda softens temporary and permanent water hardness
- Reacts with calcium sulphate- "locking up" calcium ions-insoluble calcium carbonate is made
- Temporary hardness is removed by boiling- hydrogen carbonate decomposes in hot water to form limescale (calcium carbonate) water and CO2
- Measured by a lather (number of flakes needed- a measure of water hardness)
- Soap is shaken in water-calcium ions react-scum
- Soap reacts with all calcium ions. More soap=stable lather
- Soap is shaken in water-calcium ions react-scum
- Calcium hydrogencarb-onate dissolves to form temporary water hardness
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