Complexometric Titration of Cadmium

The cadmium complex with EDTA is nearly as stable as that of zinc. In the direct titration, xylenol orange is a suitable indicator and hexamine is used to buffer die solution. 

Prepare 0.05 M solution of purest cadmium sulphate or nitrate. Pipette 25.0 cm, dilute widi 50 cm of water and add 3 drops of xylenol orange indicator and then one drop of dilute sulphuric acid to turn the colour to yellow. Then introduce powdered hexamine with agitation until the colour is clearly red. Alternatively add a 15% solution of 

The end-point is more easily detected by high frequency titration. Use 0.01 M solution of cadmium salt and 0.01 M solution EDTA. Plot the instrument reading against the volume of EDTA. The inverted V shaped plot has a maximum at the end-point. 

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