03:-   To Find The pH Of Given Samples

 Aim:- To determine the pH of given sample.

Requirement:- Sample, beaker, beret, beaker, chemical and                                                    indicator etc. 

Procedure :- First we added 10 gm of soil in a beaker then we added 25 ml distal water in beaker and kept it for about 5 minutes. Then we started machine to take the reading, first we calibrated the pH by using chemical from bottle no. 1 then placed the pH rod in soil and took the reading of the sample.

Observation :- In pH machine the reading of soil is mostly upto 6.5 –                                                    7.5.

Conclusion :- By this we can check several samples pH
                                            1. Tap water
                                            2. Distal water
                                            3. Soil
                                            4. Lemon etc.

                           04:- Chemical oxygen demand

Aim :– To take COD of given samples

Requirement:- Test-tube,  Pipit,  Beaker, Conical  flask, Weight machine,  Funnel.

Procedure:-First take three test-tube , keep one as blank other two for samples. To take COD of the samples first add stones in the test-tube, then take mercury sulphate about 0.4 gm, then add 40 ml distal water in blank in second and third add 20 ml distal water . 
Then add 0.25 N ( potassium dichromate) about 10 ml and S2HO4 about 30 ml in sample as well as in blank. Then give a oil bath for 2 hours about 150 degree celcious, took 500 ml flask added the sample one drop of ferrous solution in flask. We added ammonium sulphate in the beret , then tit-rate till the color of  the sample changes and took the reading by the formula.
     FORMULA: COD= (blank-sample) X 0.255 X 8000

Observation :- Blank = 9.5
                                             Grey water = 17.5 – 9.5= 8
                                             Azolla = 27.1 – 17.5= 9.3 

BLANK 9.5  9.5  9.5
 GREY WATER 17.5 17.5-9.5  8
AZOLLA 27.1 27.1-17.5 9.3