Zusammenfassung der Ressource
Hard and Soft water
- 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
- 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
- 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
- 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