Hard and Soft water

Hard and Soft water

1. What is hard water

   • Hard water contains Calcium(Ca2+) and Magnesium(Mg2+) ions.
   • The hardness can be temporary or permanent
   • Temporary
     • Contains Ca or Mg hydrocarbonates
     • Hardness can be removed by boiling
   • Permanent
     • Ca or Mg sulfates and/or chlorides
     • Harness cannot be removed by boiling

2. Testing for hardness

   • You can tell the difference with how well it lathers with soap
   • Hard to produce lather in hard water, soft water its easy
   • If water produces more lather after boiling it must be temporary hard water
   • It is possible for a water sample to have both temporary and permanent hardness

3. Softening hard water

   • Boiling temp water hardness by converting hydrocarbons of calcium and magnesium into carbonates which are insoluble and form a percipitate
     • This causes limescale in kettles and hot water pipes
   • Permanent harness can be removed in two ways
     • Adding sodium carbonate. The calcium and magnesium ions bond with the carbonate ions, meaning that less detergent has to be used. This is cheap, but deposits still form
     • Passing the water through an ion exchange column. This removes the calcium and magnesium ions and replaces then with sodium ions, which do not cause hardness. This is effective but expensive

4. Adv and Disadv of hard water

   • Advantages
     • Many people say that hard water tastes better then soft water
     • Calcium and magnesium important in diet, hard water provides these
     • Magnesium in hard water may give some protection against heart disease
   • Disadvantages
     • Temporary hard water produces limescale which clogs up water pipes and appliances
     • Hard water needs more soap to clean effectively
     • Treating hard water in order to save soap, produces deposits on washed clothes