Determination of Anions with EDTA

Using EDTA alsopennits us to quantitatively determine some anions. We can proceed in two ways. 

The second approach is much like the preceding method. The precipitate in which the anion to be determined is engaged is treated with a reagent that stoichiometri-cally liberates a cation that is titrated with a standard solution of EDTA. Hence, a halide (except the fluoride) or the thiocyanate ion is precipitated as the corresponding silver salt. The latter is treated with a solution of potassium tetracyanonickelate K2 [Ni(CN)4]. The silver salt dissolves into this solution with liberation of one nickel ion Ni + for two ions X . Ni + is titrated with EDTA in the presence of murexide. The reaction constituting the basis of the process is 

Some practical points concerning titrations with EDTA are sufficiently important to be briefly underlined  

29 Complexometiy III Metal Cation Indicators and Types of EDTA Titrations 

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