S.4 Chem. Electrolysis Caltec S.4

1 EFFECTS OF ELECTRICITY ON SUBSTANCES Electricity is a form of energy produced as a result of flow of electrons through materials. Investigation of electrical conductivity through solid materials Examples of such materials include: copper wire, zinc wir e, plastic, graphite, rubber. Procedure Connect the copper wire to the batteries through the bulb and the switch as shown below. Results The bulb produced light on complete connection with copper and zinc. Conclusion Copper and zinc wires con duct electricity and they are called conductors . A conductor is a substance in solid form which can conduct electricity. Examples include; all metals and graphite (the only non metal that can conduct electricity. When the above experiment was repeated us ing rubber and plastics, the bulb did not light indicating that they do not conduct electricity and are referred to as insulators or non conductors . A non conductor is a substance in solid form that does not conduct electricity. Examples are all non meta l except graphite. Metals conduct electricity because they have delocalized, free or mobile electrons but non metals do not have these delocalized electrons as they are all locked up in bond formation Investigation of electrical conductivity through liqu id substances in solution Examples: ethanol, urea, hydrochloric acid, copper (II) sulphate, ethanoic acid, water, ammonium hydroxide. Procedure Put the liquid under investigation in an electrolytic cell. Dip two rods in the liquid which can either be a metal or carbon(graphite) called electrodes Connect the electrodes using a conductor to a bulb via a switch to the source of power (the batteries) as shown below. 2 Close the switch. Repeat the experiment with hydrochloric acid, ethano l, ethanoic acid, water, urea, ammonium, ammonium hydroxide. Results When ethanol and urea were used there was no light produced indicating that they …