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ESTIMATION OF TOTAL HARDNESS OF WATER BY EDTA METHOD
AIM
To estimate the total hardness present in the given water sample using approximately 0.01 M ethylenediamine tetraacetic acid (EDTA) solution.
PRINCIPLE
The estimation of hardness is based on complexometric titration. These titrations are particularly useful to determination of a mixture of different metal ions in solution. Calcium or magnesium ions present in the water sample in the presence of ammonical buffer solution form an unstable wine red colour complex with Eriochrome Black T (EBT) indicator. When the EDTA solution is added, it reacts with the calcium or magnesium ions present in water to form a stable deep blue colour (M–EDTA) complex and releases the free indicator.
EDTA metal ...
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