|Equivalent Weight||169.87 (Molar = Normal)|
Silver Nitrate solutions are used almost exclusively for the determination of Halides, i.e., Chloride, Bromide and Iodide. Silver Nitrate solutions can be standardized potentiometrically, or by using the Mohr method or the Volhard method.
The Mohr method uses a Chloride standard and Potassium Chromate Indicator. The reactions for the Mohr titration are:
Ag+ + Cl- → AgCl (white precipitate)
2 Ag+ (excess) + CrO42- → Ag2CrO4 (red precipitate at endpoint)
The Volhard method uses a standard Thiocyanate solution and Ferric Alum Indicator. The reactions for the Volhard titration are:
X- + excess AgNO3 → AgX (precipitate) + AgNO3
X = Cl, Br, I
SCN- + AgNO3 → AgSCN (white precipitate) + NO3-
excess SCN- + Fe3+ → [FeSCN]2+ (red complex at endpoint)
Less accurate determinations using adsorption indicators are employed when analyzing for mixtures of Halides. Silver Nitrate can also be used to titrate Cyanide solutions. In this case, a Silver-sensitive indicator, p-Dimethylaminobenzalrhodanine, is used.