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r of the value indicated by broad range of pH papers and dip them seperately in the water samples, AIM: Collect water from two different water bodies around you and study them for pH., REQUIREMENTS, Water samples from two different sites such as pond water, tap water, tube well water, rive, canal water etc., test tubes, pH papers., PROCEDURE, Take different water samples in different test tubes. Dip a small piece of broad range pH pape, in each of the water samples. Match the colour of the pH paper with the colour scale given on the pr, paper booklet. This gives an approximate pH. For more accurate value, take piece of narrow range of pi, paper of the value indicated by broad range of pH papers and dip them seperately in the water sample, Match the colour of the papers with the pH scale given on the pH paper booklet. This will give the cone, value of the pH of water samples.
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OBSERVATIONS, Record the pH of different water samples in the observation table., S. No., Water samples, pH, PRECAUTIONS, Take clean and dried test tubes., 2. Dry the pH papers before comparing the colour with the colour scale., 1 Match the colour carefully and determine pH accurately., EXPERIMENT 4.2, AIM: Collect water from two different water bodies around you and study them for clarity and, presence of particulate matter (suspended pollutants) in different samples of water., REQUIREMENTS, Cardboard box, electric bulb or torch, beaker, different samples of water., PROCEDURE, Take a cardboard box and prepare a Tyndal set-up from it to test turbidity. Tyndal set-up can, be prepared by making a pencle size hole in the cardboard box and fixing a light source (electric bulb/, torch) on the other side of the box., Place the beaker containing the samples of water one by one. Make your laboratory dark and, ight the bulb/torch. Observe the sample of water through the hole. Compare the turbidity of different, water samples., OBSERVATION, Suspended particulate pollutants (such as clay particles, organic matter, bacteria, unicellular, organisms etc.) may be observed.
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Presence of large number of microorganisms indicates the presence of organic pollutants in water., Box, Suspended, particles, Torch, Beaker with, water, Fig. 4.1. Tyndal set-up showing presence of particulate pollutants in water., PRECAUTIONS, 1. The hole in the cardboard box should not be large., 2. The light source should be of sufficient intensity., EXPERIMENT 4.3, AIM: To study different water samples for the presence of living organisms., REQUIREMENTS, Water samples (such as pond water, river water, canal water etc.) microscope, glass slides, dropper, methylene blue, spirit lamp, etc., PROCEDURE, Take a clean slide and put a few drop of water seperately from different water samples. Spread the, drops to make a thin film of water on the slide. Allow it to dry. Pass the lower side of the slide through, the flame of spirit lamp two or three times to fix the living organisms present in water on to the slide, Add a few drop of a methylene blue on the slide. Leave the slide for two minutes. Wash the slide and, observe the slide under the microscope., OBSERVATION, algae,, A number of types of microorganisms (such as bacteria, protozoa, diatoms, some, cyanobacteria) are observed. Different types of organisms present in water samples are given in, Figs. 4.2 and 4.3., CONCLUSION, in
