NCERT Book Class 9 EVS Quality of water

17. Quality of water

Background

The drinking water that we get is contaminated with various dissolved substances such as calcium, iron, aluminium salts, etc. which often cross the permissible limits. The water in extreme cases may receive effluents from factories,  small textile, printing and dyeing units or farm runoffs.Outright harmful constituents such as arsenic, fluorides, copper, mercury and lead are also present in drinking water in wide parts of India. These substances cause serious ailments. It is worthwhile to find out by simple means the presence of the various impurities.

Methodology

1. Collect samples of water (about 200 ml) from different sources, e.g. handpumps, wells, tube wells, tanks, ponds, rivers and taps.

2. Filter the suspended matter from the water samples by passing through a cotton plug kept in a funnel.

3. Now take 100 ml of each sample separately.

4. Evaporate water from each sample till dry. For this, take water in a steel vessel and heat gently till all the water has evaporated.

5. Collect the dry mass separately and weigh it.

6. Identify the impurities by analysing the solid residue, if possible.

Conclusion

Draw your conclusion about the amount of dissolved matter in water.

Follow-up

If possible, find out with the help of experts/scientists the harmful constituents present in the dry mass and present it before the class and community.

Please refer to attached file for NCERT Class 9 EVS Quality of water