Extracting aluminium

• What does the reactivity series show?

  It shows metals in order of reactivity.
• How is the reactivity of a metal related to its tendency to form ions?

  The reactivity of a metal is related to its tendency to form positive ions.
• What is the method used to extract iron and aluminium from their ores?

  They are extracted using various methods.
• Why must aluminium be extracted using electrolysis?

  Because aluminium is more reactive than carbon.
• What is the relationship between the abundance of aluminium and its cost?

  Aluminium is more abundant than iron but is more expensive.
• Why is aluminium extraction expensive?

  It requires large amounts of electrical energy.
• What is the first step in the electrolysis of aluminium oxide?

  Aluminium ore is treated to produce pure aluminium oxide.
• What are electrolytes used in electrolysis?

  They are ionic compounds that conduct electricity when molten or dissolved.
• Why must aluminium oxide be molten to act as an electrolyte?

  Because aluminium oxide is insoluble in water.
• What is the melting point of aluminium oxide described as?

  The melting point of aluminium oxide is high.
• How is the cost of aluminium extraction reduced?

  By dissolving powdered aluminium oxide in molten cryolite.
• What is the purpose of cryolite in the extraction process?

  Cryolite lowers the melting point of aluminium oxide.
• What happens to the anodes during the electrolysis of aluminium?

  The anodes are gradually oxidised and must be replaced frequently.
• What is the half equation for the oxidation of oxide ions during electrolysis?

  2O$^{2-} \rightarrow O_2 +$$4e^{-}$
• What is the half equation for the reduction of aluminium ions during electrolysis?

  Al$^{3+} +$$3e^{-} \rightarrow Al$
• What are the key steps in the electrolysis process for extracting aluminium?

  • Aluminium oxide is treated to produce pure aluminium oxide.
  • Electrolytes are ionic compounds that conduct electricity.
  • Aluminium oxide must be molten to act as an electrolyte.
  • Cryolite is used to lower the melting point of aluminium oxide.
  • During electrolysis, aluminium ions gain electrons at the cathode, and oxide ions lose electrons at the anode.
• What are the costs associated with aluminium extraction?

  • High energy costs due to electrolysis.
  • Replacement costs for oxidised carbon anodes.
  • Costs related to the melting of cryolite.
• What is the definition of an ore?

  An ore is a rock containing enough quantities of a mineral for extraction to be possible.
• What is the definition of an electrolyte?

  An electrolyte is a substance that conducts an electric current when molten or in solution.
• What is the definition of an ionic compound?

  An ionic compound occurs when a negative ion joins with a positive ion.
• What is the definition of a cathode?

  A cathode is the negative electrode during electrolysis.
• What is the definition of an anode?

  An anode is the positive electrode during electrolysis.
• What is the definition of oxidation?

  Oxidation is the gain of oxygen or loss of electrons by a substance during a chemical reaction.
• What is the definition of reduction?

  Reduction is the loss of oxygen, gain of electrons, or gain of hydrogen by a substance during a chemical reaction.