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A 5ml sample of waste water was refluxed with 30ml of potassium dichromate solution and after refluxing the excess unreacted dichromate required 23ml of 0.1M FAS solution.
written 7.8 years ago by gravatar for teamques10 teamques10 ★ 67k •   modified 7.8 years ago

A blank of distilled water on refluxing with 30ml of dichromate solution required 36ml of 0.1M FAS solution. Calculate the COD value of the waste water.

FE > Semester 1 > Applied Chemistry 1

Marks : 03

Years : DEC 2015

engineering chemistry
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written 7.8 years ago by gravatar for teamques10 teamques10 ★ 67k

Given:

$V_b=36 ml \\ V_t=23 ml \\ V_e=30 ml \\ N = 0.1 \\ COD=\dfrac {(V_b-V_t×N×8)×1000}{V_e }\\ =\dfrac {(36-23×0.1×8)×1000}{V_e } \\ =\dfrac {13×8×100}{30} \\ =\dfrac {10400}{30} \\ =346.67 $

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