4.7 Electrolysis 1 - Introduction

• What is the main topic of today's video?

  Electrolysis
• What does electrolysis allow us to do with insoluble ionic compounds?

  It allows us to separate the elements in insoluble ionic compounds
• What is an electrolyte?

  A liquid or solution that contains an ionic compound
• Why must the ions in the electrolyte be free to move?

  To allow the electrolysis process to occur
• How would you prepare an electrolyte from a soluble compound like copper sulfate?

  Dissolve it in water to create an aqueous solution
• What must you do to prepare an electrolyte from an insoluble compound like lead bromide?

  Heat it until it melts to create a molten liquid
• What ions are present in molten lead bromide?

  Positive lead ions and negative bromide ions
• What are the electrodes used in electrolysis generally made of?

  Metal or carbon
• What is the positive electrode called?

  Anode
• What is the negative electrode called?

  Cathode
• What is the purpose of the power supply in electrolysis?

  To drive the flow of electrons between the electrodes
• What does the term electrolysis literally mean?

  Splitting up with electricity
• What happens to the negative bromide ions during electrolysis?

  They are attracted to the positive anode and discharged
• What do bromide ions form when they are discharged at the anode?

  Bromine gas
• What happens to the positive lead ions during electrolysis?

  They are attracted to the negative cathode and discharged
• What is formed at the cathode during electrolysis of molten lead bromide?

  Pure lead
• What is the process occurring at the anode with bromide ions?

  Oxidation to bromine, losing one electron each
• What is the process occurring at the cathode with lead ions?

  Reduction to form pure lead by gaining two electrons
• How do electrons move during the electrolysis process?

  From the negative bromide ions to the positive lead ions
• What is the overall process of electrolysis in molten lead bromide?

  • Electric current passes through the electrolyte
  • Negative bromide ions are oxidized at the anode to form bromine gas
  • Positive lead ions are reduced at the cathode to form pure lead
  • Electrons flow from bromide ions to lead ions
• What will be covered in the next two videos following this one?

  1. Electrolysis of metal oxides to extract pure metal
  2. Electrolysis of aqueous solutions