6ml of Waste Water Was Refluxed with 25ml Ofk2cr20 7 Solution and After Refluxing the Excess Unreacted Dichromate Required 20ml of 0. 1 N Fas Solution. a Blank of Distilled Water on Refluxing with 25 - Applied Chemistry 1

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Answer in Brief

6ml of waste water was refluxed with 25ml ofK2Cr2 O7 solution and after refluxing the excess unreacted dichromate required 20ml of 0. 1 N FAS solution. A blank of distilled water on refluxing with 25 ml of K2Cr2O7 solution required 35ml of 0. 1 N FAS solution . Calculate the COD of the waste water sample.

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Solution

Given data:-            Vb=35mI,                Vt=20ml,

                                N=O. 1N,                  Y=6ml.

To find:-                  COD{Chemical Oxygen Demand).

Formula:-               `COD = ((Vb - Vt) xx N xx 8000)/(Y)` mg/L

Solution:-               `COD = ((35-20) xx 0.1 xx 8000)/6` mg/L

                               COD = 2000mg/L

Concept: COD- Definition and Significance
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2016-2017 (December) CBCGS
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