Ethyl iodide (also iodoethane) is a colorless, flammable chemical compound. It has the chemical formula C₂H₅I and is prepared by heating ethanol with iodine and phosphorus. On contact with air, especially on the effect of light, it decomposes and turns yellow or reddish from dissolved iodine. It may also be prepared by reaction between hydroiodic acid and ethanol distilling off the ethyl iodide. Ethyl iodide should be stored in copper powder to avoid fast decomposition, though even with this method samples don't last more than 1 year.