1. Water and Humans go hand in hand!!!

2. Importance of Water to human life Next to oxygen, water is the most essential element to human life; the body usually cannot survive longer than several days without water (a maximum of 1 week). Water is essential to the functioning of every single cell and organ system in the human body. Water makes up greater than 2/3 of the weight of the human body; the brain is 75% water, blood is 83% water, bones are 22% water, muscles are 75% water, and the lungs are 90% water. Africa and some parts of India do not have treated water supplies… This causes many harmful diseases and unnecessary problems.

3. How is water treated? The process of the treatment of drinking water can be divided into four main parts: Screening Clarification Filtration (to remove larger particles) Disinfection

4. Hard and Soft waters Hard: Does not easily form a lather with soap Contains Calcium Compounds Contains Magnesium Compounds Contains Iron Compounds Can be found in places such as London, Lincoln and Bristol. Soft: Forms a lather easily No Calcium Compounds No Magnesium Compounds No Iron Compounds Can be found in places such as Swansea, Leeds and Cardiff.

5. Advantages and Disadvantages of Hard and Soft Water Hard Advantages: Calcium ions in the water are good for children’s teeth and bones. Hard water is used in the brewing of beer because of the taste dissolved salts give to the beer. Disadvantages: Soap is wasted, as it does not work effectively with this water type. Hard water tastes unpleasant in comparison to soft water. Soft Advantages: Forms a lather easily with soap Tastes pleasant Disadvantages: Does not have extra minerals as Hard water does Therefore does not decrease numbers of chances of heart disease

6. How can temporarily hard water and permanent hard water be softened? Temporarily Hard water Boil the water!! Boiling water is only an effective method of softening small volumes of water. It is time consuming and expensive for large quantities. Permanently Hard water Cannot be reversed by boiling the water so there are two other methods: 1.Using washing soda! 2.Using an Ion exchange column!

7. Softening Temporary Hard Water This is caused by calcium or magnesium hydrogen-carbonate. It can be removed by boiling the water. Calcium hydrogen carbonate = calcium carbonate + water + carbon dioxide. This reaction is the opposite of when hard water forms. Boiling water is only effective when softening small amounts of water. It is time consuming and expensive for larger qualities.

8. Using Washing soda Substance added to washing water to ‘soften’ hard water. The calcium and magnesium ions in hard water react with the carbonate ions from the sodium carbonate and a precipitate of calcium carbonate results. Na2CO3(aq) + CaSO4(aq) ® CaCO3(s) + Na2SO4(aq) In the above process, the scale that’s formed is easily removed because it is insoluble. The Na2So4 (aq) that has formed dissolves and so the hardness has been removed.

9. Using an Ion exchange column http://www.yenka.com/freecontent/attachment.action?quick=v2&att=2226 Hard water passes through a column containing a suitable resin in small granules. The column contains an excess of sodium ions. When the hard water passes through the column, the Ca2+ ions in the water are exchanged for Na+ concentrated solution of sodium chloride through the column. Na+ ions do not cause hardness and so the water is soft. Domestic water softeners work on this principal.