Titrimetry

• The two most common reductants are: Iron(II) and Sodium Thiosulfate.
• Sodium peroxide and hydrogen peroxide are convenient oxidizing agents.
• Ammonium peroxydisulfate is also a powerful oxidizing agent. In acidic solution, it converts chromium(III) to dichromate, cerium(III) to cerium(IV), and manganese(II) to permanganate.
• Sodium bismuthate is a powerful oxidizing agent capable of converting manganese(II) quantitatively to permanganate ion.
• A number of metals such as zinc, aluminum, cadmium, and silver are good reducing agents and have been used for prereduction of analytes.
• Titrations with silver nitrate are sometimes called argentometric

  titrations
• Hard water contains calcium, magnesium, and heavy metal ions that form precipitates with soap.
• Volhard Method is one of the most common argentometric methods. In this method, SILVER IONS are titrated with a standard solution of THIOCYANATE ION. IRON(III) serves as the indicator. The solution turns RED with the first slight excess of thiocyanate ion.
• In the Mohr method, SODIUM CHROMATE serves as the indicator for the argentometric titration of CHLORIDE, BROMIDE, and CYANIDE IONS. SILVER IONS react with CHROMATE to form the BRICK-RED SILVER CHROMATE precipitate in the equivalence-point region.
• The Fajans method uses an adsorption indicator, an organic compound that adsorbs onto or desorbs from the surface of the solid in a precipitation titration.
• EDTA = Ethylene Diamine Tetra Acetic Acid
• EDTA has six potential sites for bonding a metal ion: the four carboxyl groups and the two amino groups
• (Indicator EDTA titrations) Eriochrome Black T is a typical metal-ion detector.