Analytical Chemistry

Table 5.11 Some additional aminocarboxylic acid ligands

provides the basis for their direct titration. Excess silver ions react to produce AgCN

which has a low solubility (Ksp = 1.2 × 10 –^16 ) showing a precipitate at the end point of the titration. The

cyanide complexes (M = Cu, Zn, Co, Ni) are significantly more stable than and
may be determined in a back titration procedure. Excess cyanide is added to a slightly alkaline solution
of the metal and the excess cyanide titrated with silver nitrate.

Precipitation Titrations

Titrimetric reactions in which the product is of low solubility have been used for very many years.
Titrations employing such reactions are known as precipitation titrations. Although not of widespread
importance, for a