Electrolysis part 2

• Why do metals often exist as oxides?

  Because they react with oxygen in the environment
• What process is used to extract reactive metals from their oxides?

  Electrolysis
• What is the purpose of reducing the metal in the oxide?

  To remove the oxygen and isolate the pure metal
• Which method is a cheap way to reduce metal oxides?

  Reduction with carbon
• For which metals does reduction with carbon work?

  Metals less reactive than carbon, like zinc, iron, and copper
• What is the main drawback of using electrolysis for metal extraction?

  It requires a lot of energy and is expensive
• What is the definition of electrolysis?

  A process that separates ionic compounds into pure elements using electric current
• What must happen to aluminium oxide before electrolysis can occur?

  It must be melted into a molten state
• What is the melting point of aluminium oxide?

  Over 2000 degrees Celsius
• What mineral is mixed with aluminium oxide to lower its melting point?

  Cryolite
• What equipment is needed to set up electrolysis for aluminium oxide?

  A beaker, two carbon electrodes, and a power source
• What is produced at the cathode during the electrolysis of aluminium oxide?

  Molten aluminium metal
• What happens to oxygen ions at the anode during electrolysis?

  They lose electrons and are discharged as oxygen atoms
• What is the half equation for the reaction at the cathode?

  Aluminium ions combine with electrons to form aluminium
• What mnemonic helps remember the difference between oxidation and reduction?

  Oil rig
• What is the half equation for the reaction at the anode?

  Oxygen ions form oxygen atoms plus electrons
• What does oxidation refer to in terms of electrons?

  Loss of electrons
• What does reduction refer to in terms of electrons?

  Gain of electrons
• What is the overall equation for the electrolysis of aluminium oxide?

  Aluminium oxide (liquid) forms aluminium (liquid) and oxygen (gas)
• What are the steps involved in the electrolysis of aluminium oxide?

  1. Purify aluminium oxide from bauxite
  2. Mix with cryolite to lower melting point
  3. Melt the mixture to create molten aluminium oxide
  4. Set up electrolysis equipment with electrodes and power source
  5. Conduct electrolysis to produce aluminium and oxygen
• What are the roles of the anode and cathode in the electrolysis of aluminium oxide?

  • Anode: Positive electrode where oxygen ions are oxidized to oxygen gas
  • Cathode: Negative electrode where aluminium ions are reduced to form molten aluminium
• What are the characteristics of the ions in molten aluminium oxide during electrolysis?

  • Contains oxygen ions (O$^{2-}$) and aluminium ions (Al$^{3+}$)
  • Ions are free to move, allowing for conduction of electricity