c DISPLACEMENT OF HYDROGEN FROM ACIDS BY METALS i Pour 5 cm of the acids in the table below into testtubes Place a piece of metal foil in each testtube Note the formation of hydrogen and compare the different rates at which the bubbles are formed Rate of formation of hydrogen gas  very rapid rapid slight very slight none Metal b 3M hydrochloric acid c 3M sulphuric acid Magnesium b Very rapid c Rapid Aluminium b Slight c None Zinc b Moderate c Slight Iron b Very slight c Very slight Tin b None c None Lead b None c None Copper b None c None ii Recover the zinc after the reaction has ceased Evaporate the solution to leave zinc sulphate crystals Dissolve the colourless zinc sulphate crystals in water and put two carbon electrodes central poles of dry cell batteries in the solution Connect the electrodes to a 6volt or 12 volt DC supply Zinc forms rapidly on the cathode