Original: Copper ( I ) iodide can be prepared by heating iodine and copper in concentrated hydriodic acid , HI . In the laboratory however , copper ( I ) iodide is prepared by simply mixing an aqueous solution of sodium or potassium iodide and a soluble copper ( II ) salt such copper sulfate .
Simplified: Copper does not form a stable copper ( II ) iodide ; copper ( II ) iodide breaks down right away to make copper ( I ) iodide and iodine .