CHAPTER 15: ENVIRONMENTAL CHEMISTRY II: WATER

  • Describe the occurrence of water and its importance in the environment including industry.
  • Review our dependence on water and the importance of maintaining its quality.
  • Describe the composition and properties of water.
  • Differentiate among soft, temporary, and permanent hard water.
  • Describe methods for eliminating temporary and permanent hardness of the water.
  • Identify water pollutants.
  • Describe industrial wastes and household wastes as water pollutants.
  • Describe the effects of these pollutants on life.
  • Describe the various types of waterborne diseases.

Where does the water in your kitchen and bathroom come from? Because water comes from different sources, it varies in quality. Would you drink water that has colour, bad taste or unpleasant odour? In the morning when you get up, what do you do? You brush your teeth, take shower, flush the toilet etc. What happens to the water that goes down the drain? Can you use this water again? Waste water is often dumped into open gutters and allowed to run directly into streams, rivers and oceans. This practice spreads diseases and threatens aquatic life also. How? This you will learn in this chapter. The presence of disease causing bacteria affects the quality of water. Water from both public and private supplies often needs some kind of treatment to ensure that it is clean and safe to drink. Waste water should also be passed through some treatment process to remove un-wanted substances, before it is released into lakes, rivers or oceans. Otherwise, it would also affect marine life and through food chain, the human beings

Science Titbits

           To overcome the problem of scum formation in hard water, detergents have been produced. Detergents do not produce scum. This is because they do not react with calcium or magnesium ions present in hard water. Also, detergent molecules are biodegradable. Bacteria can easily break these molecules, So they do not persist in the environment.