All titration which involves the direct titration of Iodine with a reducing agent are grouped under lodimetry. Iodimetry is employed to determine the strength of reducing agent such as sodium thio sulphate I_(2) + 2Na_(2)S_(2)O_(3) rarr 2I^(-)+S_(4)O_(6)^(-) If iodine is liberated as a result of chemical reaction involving oxidation of an idodide ion by a strong oxidizing agent in neutral or acidic medium the liberated iodine is then titrated with reducing agent. This titration is called lodometry. Todometry is used to estimate the strength of oxidizing agent. For example the estimation of Cu^(++)with thiosulphate. Cu^(+ +) +I^(-) Cu_(2)I_(2)+I_(2) , I_(2)+S_(2)O_(3)^(-) rarrS_(4)O_(6)^(-) +I^(-) Starch used as indicator near the end point which form blue colour complex with I_(3)^(-) . The blue colour disappears when In the reaction, 2CuSO_(4) +4KI rarrCu_(2)I_(2) + 2K_(2)SO_(4)+I_2the ratio of equivalent weight of CuSO_4to its molecular weight is: