HARD WATER

HARD WATER

1. Soft Water

   • Produces a lather when it reacts with soap
   • comes from peat or igneous rock sources, such as granite but may also come from sandstone sources, since such sedimentary rocks are usually low in calcium and magnesium.

2. Permanently Hard Water

   • Caused by the presence of dissolved calcium sulfate
   • CAN BE SOFTENED BY:
     • Adding washing powder (sodium carbonate)
       • The added carbonate ions react with the calcium and magnesium ions. The calcium and magnesium ions are no longer dissolved in the water.
     • Running water through 'ion exchange columns'
       • The columns have sodium/hydrogen ions and exchange them for the calcium and magnesium ions in the water

3. Hard Water

   • The scum produced is insoluble
   • Forms scale when heated
     • Acts as a thermal insulator so a kettle (for example)would take longer to boil
     • The build up eventually results in the blocking of pipes
     • This reduces the efficiency of the appliance, therefore they will need to be regularly replaced; costing money
   • Calcium ions are good for healthy teeth and bones. People drinking hard water are less at risk of developing heart disease
   • Calcium and magnesium ions make the water 'hard'
     • The calcium and magnesium ions are dissolved from rocks (such as limestone, chalk and gypsum) as magnesium sulfate and calcium sulfate

4. Temporarily Hard Water

   • CAN BE SOFTENED BY:
     • Adding washing soda (sodium carbonate)
       • The added carbonate ions react with the calcium and magnesium ions. The calcium and magnesium ions are no longer dissolved in the water
     • Running water through 'ion exchange columns'
       • The columns have sodium (or hydrogen) ions and exchange them for the calcium and magnesium ions in the water
   • Caused by the presence of hydrogencarbonate ions
   • Removed by boiling
     • The hydrogen-carbonate ions decompose to form calcium carbonate which is insoluble. This is called limescale.

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