Electrolysis

• Investigating what happens when aqueous solutions undergo electrolysis

  1. Pour approximately 50 cm^3 of copper(II) chloride solution into a beaker

  2. Place a plastic petri dish with two holes over the beaker

  3. Insert a carbon graphite rod into each hole (electrodes)

  4. Attach crocodile leads to the rods and connect to a low-voltage power supply

  5. Select 4 volts on the power supply and switch it on
• Electrodes


  • Carbon graphite rods are unreactive (inert)
  • The two electrodes must not touch each other to avoid a short-circuit
• Copper is less reactive than hydrogen


  Copper is discharged at the cathode
• Electrolyzing a solution containing a halide ion


  The halogen is discharged at the anode
• Chlorine gas is produced at the anode during electrolysis of copper(II) chloride solution
• Holding damp blue litmus paper near the anode shows the gas is chlorine (it becomes bleached)
• Electrolyzing sodium chloride solution

  1. Pour approximately 50 cm^3 of sodium chloride solution into a beaker

  2. Turn on the low-voltage power supply
• Electrolyzing sodium chloride solution

  Chlorine gas is produced at the anode, hydrogen gas is produced at the cathode
• Hydrogen gas can be tested by collecting it and testing with a lit splint (produces a squeaky pop)