The solution containing positive divalent copper ions is blue, Zeng Qing is a copper compound, and Zeng Qing is a copper compound; According to the fact that there are two elements in the compound and the other element is chlorine, the compound is CuCl _ 2. According to the order of metal activity, the reaction equation between CuCl _ 2 and Fe is written as CuCl _ 2+Fe θ FeCl _ 2+Cu.
So, the answer is: copper; CuCl2+Fe═FeCl2+Cu.