Aluminium Oxide

• What is the purpose of electrolysis in metal extraction?

  To extract reactive metals from their oxides
• What must be done to metal oxides before extracting metals?

  They must be melted into molten ionic compounds
• Why do metals often exist as oxides?

  Because they react with oxygen in the environment
• Which method is used to reduce metals less reactive than carbon?

  Reduction with carbon
• What is the limitation of using carbon for reduction?

  It only works for metals less reactive than carbon
• What is electrolysis?

  A process to separate ionic compounds using electric current
• What is required for electrolysis to work effectively?

  The ions must be able to move freely
• What is the state of aluminium oxide at the start of electrolysis?

  It is solid
• What is the first step in preparing aluminium oxide for electrolysis?

  Purify it from bauxite ore
• What mineral is mixed with aluminium oxide to lower its melting point?

  Cryolite
• Why is cryolite used in the electrolysis process?

  To lower the melting point of aluminium oxide
• What equipment is needed for the electrolysis of molten aluminium oxide?

  A beaker, electrodes, and a power source
• What happens to oxygen ions at the anode during electrolysis?

  They lose electrons and form oxygen atoms
• What is produced at the cathode during electrolysis of aluminium oxide?

  Molten aluminium metal
• What is the overall reaction of electrolysis of aluminium oxide?

  Aluminium oxide forms aluminium and oxygen
• What does the mnemonic "oil rig" help remember in electrolysis?

  Oxidation is loss, reduction is gain
• How many electrons are released at the anode during the oxidation of oxygen ions?

  Four electrons
• What is the charge of aluminium ions in the electrolysis process?

  3 plus
• What is the state of aluminium after the electrolysis process?

  It is a liquid
• 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 make it molten
  4. Set up electrolysis equipment
  5. Pass electric current through the molten electrolyte
  6. Collect molten aluminium at the cathode and oxygen at the anode
• What are the half equations for the electrolysis of aluminium oxide?

  At the anode:

  • \( \text{2 O}^{2-} \rightarrow \text{O}_2 + 4 e^- \)

  
  

  At the cathode:

  • \( \text{Al}^{3+} + 3 e^- \rightarrow \text{Al (l)} \)
• What are the products of the electrolysis of molten aluminium oxide?

  • Aluminium (liquid)
  • Oxygen (gas)
• What is the significance of the melting point of aluminium oxide in electrolysis?

  • High melting point (>2000°C)
  • Requires cryolite to lower melting point
  • Needs significant energy for melting
• What is the role of electrodes in the electrolysis process?

  • Anode: Positive electrode, attracts negative ions
  • Cathode: Negative electrode, attracts positive ions
  • Conducts electricity through the electrolyte