Precipitation titration :
Volumetric methods based upon the formation of slightly soluble precipitate are called ” precipitation titration ” . Because of the precipitating titration based upon utilizing silver nitrate (AgNO3) as a precipitating agent, then it called ” argentimetric processes ” .
Precipitation titration is a very important , because it is a perfect method for determine halogens and some metal ions .
Titration curves for precipitation titrations :
Titration curves are represents :
1) The change in conc. of reactants throughout titration .
2) Titration error that is likely occur when using the indicators .
3) The conditions at equivalent point
End point detection precipitation titration :
1) formation of a second colored precipitate (Mohr method):
2) formation of colored complex ( Volhard method ) :
Complex formation titration
Titration curve for complexation titration :
Composition of EDTA solution as a function of pH :
Complexes of EDTA and metal ions :
Derivation of titration curves for EDTA titration :
Indicators for EDTA titration :
Titration method employing EDTA :
1) Direct titration :
2) Back – titration :
3) Displacement titration :
Solubility of precipitates
Solubility product constant (K.S.P) :
Application of KSP in precipitation :
1) Completments of precipitation :
2) Dissolution of precipitate:
3) Prevention of precipitation :
Factors effecting the solubility of precipitates :
2) Effect of hydronium ion concentration (pH) :
3) Formation of complex ion :
4) Temperature :
Effect of electrolyte concentration on solubility :
Coefficient of activity :