e ELECTRICAL ENERGY FROM CHEMICAL REACTIONS  ELECTROCHEMICAL CELLS In the preceding experiment zinc metal became zinc ions and copper ions became copper metal due to transfer of electrons from zinc metal to the copper ion To get electrical energy these electrons must flow in an external conductor from the zinc to copper The potential or voltage will reflect the greater activity of zinc over copper The current flowing will depend on the extent and rate of the reaction 284 Electrical energy from the displacement of copper by zinc Put concentrated copper sulphate solution in a beaker Connect copper foil to the positive terminal of a 5 V voltmeter Connect zinc foil to the negative terminal Dip the two metals briefly into the copper sulphate solution Note any changes in the voltmeter reading Note the maximum reading Note any changes at the copper foil and the zinc foil The voltage falls to zero after a short time because copper deposited on the zinc and caused the reaction to stop