Soft water lathers easily with soap
What does hard water produce when it reacts with soap?
Scale
Scum
What ions does hard water contain?
Calcium and magnesium
Carbon and potassium
Temporary hard water produces scale when heated
What does scale do?
Reduce the efficiency of heating systems and cause blockages
Evaporate when heated
How are calcium compounds good for our health?
Help develop strong bones and teeth. May reduce the risk of heart disease.
They do not have any particular health benefits
Help with fighting infection
Permanent hard water is not softened by boiling and does not produce scale when heated
Washing soda is sodium carbonate
How are ions precipitated out of hard water?
Sodium carbonate reacts with the magnesium and calcium ions in the hard water to form calcium carbonate and magnesium carbonate that will not react with water
Filtration
Sodium carbonate displaces the magnesium and calcium ions so the hard water turns soft
Ion exchange columns contain a resin made of sodium and hydrogen ions
How do ion exchange columns work?
The calcium and magnesium ions attach to the resin and the water no longer contains any ions
The hard water is passed through the exchange column. The calcium and magnesium ions become attached to the resin and the sodium and hydrogen ions take their place in the water. These ions do not react with soap
What methods are used to treat water
Sedimentation and filtration to remove solids
Evaporation and distillation
Why is chlorine used in the treatment of water
Because it is a law
Because chlorine kills microbes in the water
What are the issues with using chlorine to treat water?
It is poisonous and can produce toxic compounds
It is very expensive
Why is fluoride added to water?
To prevent tooth decay
It is added by the government to control the population
To help prevent heart disease
Some people think that you should be able to choose whether or not to have fluoride in your water
