Reduction of copper. Zinc (Fe) and black copper(II) oxide (CuO) powders are mixed in a stoichiometric ratio. The mixture is strongly heated in a flame of a propane Bunsen burner. Once the reaction starts, the flame is removed. The reaction then proceeds, generating its own heat. Copper metal (Cu) and zinc oxide (ZnO) are the product of this exothermic single-displacement reaction: CuO + Zn -> Cu + ZnO.