VOLHARD'S METHOD CALCULATIONS [WORKED EXAMPLE]

The Volhard method is a classical argentometric titration technique used to determine halide ions (like chloride, bromide, and iodide) by back titration with silver nitrate and potassium thiocyanate in acidic medium, with ferric ions as an indicator. It is especially useful when direct titration methods (like Mohr’s) are unsuitable due to solubility or pH issues. Argentometric titration: Relies on reactions involving silver ions (Ag⁺). Back titration: A known excess of silver nitrate is added to the halide-containing solution. Indicator: Ferric ions (Fe³⁺) form a red complex with thiocyanate (SCN⁻), signaling the endpoint. Reaction sequence: Ag⁺ + Cl⁻ → AgCl (precipitate) Excess Ag⁺ + SCN⁻ → AgSCN (white precipitate) Remaining SCN⁻ + Fe³⁺ → [FeSCN]²⁺ (red complex, endpoint).