Electrolysis

• Electrolysis (Copper II Sulfate Solution)

  • pour a set volume of copper sulfate solution into a beaker
  • place a petri dish lid over the beaker with 2 holes in
  • insert a carbon graphite rod into each hole and ensure they aren't touching
  • attach crocodile leads to rods and connect to power supply
  • switch on power supply
  • copper metal is produced at the cathode (less reactive than hydrogen)
  • oxygen and water are produced at the anode
• Electrolysis (Sodium Chloride Solution)

  • pour a set volume of sodium chloride solution into a beaker
  • place a petri dish lid over the beaker with 2 holes in
  • insert a carbon graphite rod into each hole and ensure they aren't touching
  • attach crocodile leads to rods and connect to power supply
  • switch on power supply
  • sodium is more reactive than hydrogen so hydrogen gas is discharged at the cathode
  • chlorine gas is discharged at the anode (group 7 element)
• At the cathode, if H+ ions and metal ions are present, hydrogen gas is discharged if the metal ions are from a metal more reactive than hydrogen.
• At the cathode, if the metal ions are from a metal less reactive than hydrogen, a solid layer of pure metal will be formed.
• At the anode, if OH- and halide ions (halogens) are present, molecules of the halogen present will be formed.
• At the anode, if no halide ions are present, then OH- ions are discharged and oxygen will be formed.
• If copper was produced at the cathode, a brown solid would coat the electrode.
• If hydrogen gas were produced at the cathode, effervescence, bubbles or fizzing could be observed.
• Copper ions each gain two electrons to form copper atoms at the cathode.
• To prove hydrogen gas has been produced, collect the gas and test it with a lit splint. If hydrogen is present, it will produce a squeaky pop.
• Electrolysis could not take place in solid sodium chloride because it is an ionic compound. This means it would not conduct electricity when solid because the ions are unable to move.
• Graphite is used for the electrodes because it us inert (unreactive) and it conducts electricity.
• Water in the solution provides the hydroxide ions to form oxygen.