Page 107 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

Precipitation Titrations

• They are volumetric methods based on the formation of a slightly soluble precipitate.

• The substance is determined simply by converting it into an insoluble form of known

composition by adding a standard solution of the titrant.

• The equivalence point is reached when an equivalent amount of the titrant has been

added. From the volume of the latter (E.P), the amount of the substance is calculated.

• It is a type of volumetric analysis in which some compounds or ions are determined

through the formation of insoluble salts by using a precipitating agent.

• Titration methods based upon utilizing silver nitrate (AgNO ) as a precipitating agent
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are known as Argentometric Titrations. Silver ion is extremely useful in precipitation

reactions of:

− − −
• Halides (Cl , Br , I )

− −
• Pseudohalides (CN , SCN )

Solubility Product Constant (Ksp)
An equilibrium can exist between a partially soluble substance and its solution:

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