Complexometric Determination of Copper

Copper occurs both in combined state and free state and also in many ores. The abundance of copper in earth’s crust is estimated to be 70 parts per million. The important ores of copper are: Copper pyrites or Chalcopyrite (CuFeS2), Cuprite (Cu2O) and Copper glance (Cu2S). The leading producers of copper are Chile and the United States. Nearly half of the world’s copper comes from these two countries. The next largest producers are Canada, Peru, Australia, Russia and Indonesia. About 98% of copper mined in the United States comes from Arizona, Utah, New Mexico and Nevada. In India the major copper mines are Khetri copper belt in Rajasthan, Singbhum copper belt in Bihar and Malanjkhand copper belt in Madhya Pradesh. Mining production is just 0.2% of world production. There have been various ways for volumetric determination of copper such iodometric, complexometric, elecrogravimetric, potetiometric etc among which iodometric method is the commonly adopted standard method prescribed under ISO 10258:2015. During iodometric estimation of copper two important sources of error may occur: a) loss of iodine owing to its appreciable volatility and acid solution of iodine are oxidised by oxygen from the air by the equation as shown below: