RESUMO
Orthophenanthroline [OPT] forms stable complex with Iron[II] at pH 3.5. In presence of Ce[IV] it forms a metal-ligand complex in which Fe is in the form of Fe+++ for short period when mixed in mole ratio of 1:3 [Iron: OPT]. This complex is stable for not more than 30 minutes. At the end, this complex reduces itself back to iron[II]orthophenanthroline [Fe[OPT]3]+2 complex. In present work, this property of iron[III] complex was used to oxidize I-1 to I2. Analysis of [Fe[OPT]3]+2 was carried out at 510 nm to monitor the reduction of [Fe[OPT]3]+3 complex. Copper was used as a catalyst during the described reaction to convert back [Fe[OPT]3]+2. The reaction increased with increase in copper concentration. The conversion of [Fe[OPT]3]+3 to [Fe[OPT]3]+2 followed first order kinetics