Study of water samples collected from different water bodies for their pH, clarity and presence of living organisms (microscopic/ planktonic)

Biology practical notebook class 12 Maharashtra board solutions pdf 

To study water samples for measuring all, clarity (turbidity), and presence of living organisms.  1. pll test of water sample with Litmus paper Introduction: pH is a measure of the acidity or alkalinity of water.  The pH of water is primarily decided by the salts present in the soil from where the water sample is collected.  But pH also changes due to organic matter, fertilizers, sewage, and other pollutants.  Requirements: Different water samples, sample bottle with cap.  pH papers of different ranges etc.  Procedure: Collection and preparation of sample 

Biology 

Answers

Practical Notebook
Standard XII

Class-12th

 Aim: 

To study water samples for measuring all, clarity (turbidity), and presence of living organisms.  1. pll test of water sample with Litmus paper Introduction: pH is a measure of the acidity or alkalinity of water.  The pH of water is primarily decided by the salts present in the soil from where the water sample is collected.  But pH also changes due to organic matter, fertilizers, sewage, and other pollutants.  Requirements: Different water samples, sample bottle with cap.  pH papers of different ranges etc.  Procedure: Collection and preparation of sample 

1.  Collect water samples in a clean, dry plastic jar.  
2. Cap the jar tightly and shake vigorously a few times.  
3. Allow the sample to stand for 5-10 minutes 
4. Remove the cap of the jar.  
5. dip the litmus paper in it for a second, holding it with clean dry forceps (avoid touching with your fingers.) 

Observation: 

1. Observe the color change. 
2. Match the resultant color with color code on the pH color strip.  Identify the pH and note it.  Result: 1. pH value of 6.5 to 7.5, is referred as more or less "neutral".  2 If pH is less than 6.5 then the water is acidic.  
3. If the pH is higher than 7.5 it is alkaline.  Sr.  No.  L 2.  3.  4.  Water Sample Distilled water pond water well water 4.5 7.6.  pH 2. Clarity of Water: Test of water for clarity (Turbidity): Measuring water clarity is an important part of environmental science.  Often lakes or streams contain pollutants or sediments that make the water cloudy.  This often has a bad effect on the organisms that live in such waters.  Typical sources of turbidity in drinking water include waste discharges, algae or aquatic weeds, humic acids, and other organic compounds resulting in concentrations that give water a rust-red coloration.  from the decay of plants, leaf litter, small animals, etc. in water sources and high iron and phosphorus 432 Units phen also (off were Req Fous bult Pros Coll I 2 3. 4. 5. 6. Ot 1. 2. 3. Re 1. 2. C TI

Units of Measuring Turbidity: In the late 1800's Tyndall and Rayleigh started the scientific study of light scattering.  

This phenomenon is used to understand the clarity of the water. 

 Most of the early studies considered absorption and transmittance.  Many units such as JTU (Jackson "Candle" Turbidity Units), TE / F (of formazin) European units, Kieselguhr (SiO₂) units, Nephelometric Turbidity Units (NTU), were and are being used. 

 Requirements: 

Four 1000ml beakers, distilled water, Cardboard box or some other suitable box, torch/lamp or bulb and different water samples.  

Procedure:

 Collection and preparation of sample: 

1.  Collect water samples in a clean, dry plastic jar.  
2. Avoid touching to prevent contaminating the sample.  
3.  Prepare Tyndall set up from a cardboard box as shown in the diagram.  This set-up can be made by making a hole in a cardboard box and fixing a bulb or torch on the other side of the box.  Pour distilled water in a clean beaker and use this as standard.  
4.  5. Pour different water samples in clean dry beakers and place the samples one by one and compare the turbidity.  6. Place each beaker in the Tyndall set up and observe the beaker through-hole for clarity/turbidity. 

 Observation: 

1. Observe the clarity of distilled water.  
2. Compare and note the turbidity of the samples.  
3. Record your observation as clear, less turbid, moderately turbid, and highly turbid. 

 Result:

1. The light is scattered because of the particles present in the water.  
2. More particles make water more turbid and reduce its clarity.  Conclusion: The water is turbid and hence not suitable for consumption without treatment.   33

 

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