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Estimation of Magnesium by EDTA Method
AIM
To estimate the amount of magnesium present in 100 ml of the given solution using approximately 0.01 M ethylenediamine tetraacetic acid (EDTA) solution.
Principle
The estimation of magnesium is based on complexometric titration. Magnesium ions in ammonia solution form a wine red colour complex with Eriochrome Black T (EBT) indicator. When the EDTA solution is added, it reacts with the magnesium ions and releases the free indicator. The colour of the solution changes from wine red to blue, which indicates the end point of titration.
Mg2+ + EBT → Mg – EBT
(unstable wine red colour complex)
Mg – EBT + EDTA → Mg – EDTA + EBT
(stable blue colour complex)
EDTA metal ion complex is stable at pH = 10. ...
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