P1 electrolysis

• What should you be able to describe by the end of the video?

  How to investigate electrolysis of aqueous solutions
• Why is it recommended to watch two videos before starting the protocol?

  To understand electrolysis of aqueous solutions
• What are the two aqueous solutions used in the electrolysis experiment?

  • Copper(II) chloride
  • Sodium chloride
• What is the first step in the electrolysis of copper(II) chloride solution?

  Pour 50 cm³ of copper(II) chloride solution
• What type of dish is placed over the beaker during the experiment?

  A plastic petri dish
• Why are carbon graphite rods used as electrodes?

  They are unreactive and inert
• What happens if the two electrodes touch each other?

  A short-circuit is produced
• What voltage should be selected on the power supply for the experiment?

  Four volts
• What is observed at the cathode during the electrolysis of copper(II) chloride?

  Copper is coated on the cathode
• What happens to copper during electrolysis if it is less reactive than hydrogen?

  Copper is discharged at the cathode
• What gas is produced at the anode during the electrolysis of copper(II) chloride?

  Chlorine gas
• How can you confirm that chlorine gas is produced at the anode?

  By holding damp blue litmus paper near it
• What are the two aqueous solutions that will be investigated during electrolysis in this protocol?

  Copper(II) chloride and sodium chloride
• What volume of each aqueous solution is used in the experiment?

  Approximately 50 cm³
• What type of electrodes are used in this electrolysis experiment?

  Carbon graphite rods
• Why are carbon graphite electrodes used in this experiment?

  They are unreactive (inert) electrodes
• What is the key point about the two electrodes in this experiment?

  They must not touch each other to avoid a short circuit
• What voltage is used to power the electrolysis in this experiment?

  4 volts
• Why is copper deposited at the cathode during the electrolysis of copper(II) chloride solution?

  Because copper is less reactive than hydrogen, so it is discharged at the cathode
• Why is chlorine gas produced at the anode during the electrolysis of copper(II) chloride solution?

  Because chloride ions, which are halide ions, are discharged at the anode
• How can you test for the presence of chlorine gas produced during the electrolysis?

  By holding damp blue litmus paper near the anode, which will be bleached
• Why is hydrogen gas produced at the cathode during the electrolysis of sodium chloride solution?

  Because sodium is more reactive than hydrogen, so hydrogen is discharged at the cathode
• Why is chlorine gas produced at the anode during the electrolysis of sodium chloride solution?

  Because chloride ions, which are halide ions, are discharged at the anode
• How can you test for the presence of hydrogen gas produced during the electrolysis?

  By collecting the gas and testing it with a lit splint, which will produce a squeaky pop
• What are the key differences between the products formed during the electrolysis of copper(II) chloride solution and sodium chloride solution?

  • Copper(II) chloride: Copper metal deposited at cathode, chlorine gas produced at anode
  • Sodium chloride: Hydrogen gas produced at cathode, chlorine gas produced at anode