1. Problem
Hardness of water

2. Aims: Causes of Hardness in water Hypoyhesis:The solution of hardness of water

3. Origin of hard water Hardness of Water
Hardness of Water is a measure of the amount of calcium and magnesium salts in water. Hard water contains high concentration of dissolved calcium and magnesium. While soft water contain few dissolved calcium and magnesium ions. The more calcium and magnesium in water, the harder the water.
Hardness of water is usually expressed in milligram per liter (mg/l) of dissolve calcium and magnesium carbonate.
The term hardness of water comes from the fact that it hardly form lather with soap in water.

4. Types of Hard Water
Temporary hardness of water Temporary hardness of water is a type of hardness of water caused by the presence of dissolved carbonate minerals (calcium carbonate and magnesium carbonate). When dissolved, these minerals yields calcium and magnesium cations (ca2+, mg2+) and carbonate and bicarbonate anions (CO3-, HCO3-). The present of the metal cations makes the water hard.

5. Permanent hardness of water
Permanent hardness of water is mainly due to the presence of calcium and magnesium ions in the form of soluble tetraoxosulphate (vi) and chloride.
Effect of hardness of water
Hard water leaves white deposits on teakettles and build up on hot water pipes. Its causes soaps not to lather well.it leads to wasted of energy and money.

6. Advantages of hard water
Hard water helps animals such as snails and crabs to make their shells. This shells are made mainly of calcium trioxocarbonate (iv).
Hard water tastes better than soft water because of the dissolved mineral in it.
It helps build strong teeth and bones in animals such as snails and crabs due to the presence of calcium salt in it.
Hard water can be supplied in pipes made of lead as this type of water does not dissolve lead.

7. Disadvantages of hard water
Hard water requires a lot of soap before it can form a lather in washing.
Hard water causes furring of kettles and boilers.
Hard water cannot be used in dying and tanning as the salts in it interfere with the modes of action of these process.

8. Hard water solution
Temporary hard water can be removed by boiling and using slaked lime. While permanent hard water can be removed by adding washing soda and caustic soda or by passing the hard water through an ion exchange resin.

9. References
1.^ a b Hermann Weingärtner, “Water” in Ullmann's Encyclopedia of Industrial Chemistry, 2006 December. Wiley–VCH, Weinheim. doi: / a28_001
2.^ Christian Kitsch, Hans-Joachim Heitland, Horst Marsen, Hans-Joachim Schlüussler, “Cleansing Agents” in Ullmann’s Encyclopedia of Industrial Chemistry 2005, Wiley–VCH, Weinheim. doi: / a07_137
3.^ "Lime Softening". Retrieved 4 November 2011.
4.^ Stephen Lower (July