Electrolysis

• Why is electrolysis with aluminium expensive

  Melting the compound aluminium oxide is expensive
• If we have potassium bromine what will form at the anode and cathode

  Anode- bromine

  Cathode - hydrogen
• If we have copper sulfate what will form at the anode and cathode

  Anode- oxygen

  Cathode - copper
• If we have copper chloride what will form at the anode and cathode

  Anode- chlorine

  Cathode - copper
• Aluminium ion


  Al3+
• Why is carbon graphite useful

  High melting point

  Good conductor of electricity
• Formula for aluminium oxide

  Al2o3
• Where does electrostatic attraction occur

  Between oppositly charged ions
• How do we get aluminium from aluminium oxide

  Electrolysis
• Why can't we melt alimnum

  It's too expensive with a melting point of over 2000°c
• What is an electrolyte

  It's an iconic compound molten or dissolved
• What is the purpose of electrolysis in metal extraction?

  To extract some metals from their compounds
• Why is aluminium extracted using electrolysis?

  Because aluminium is more reactive than carbon
• What is the compound from which aluminium is extracted?

  Aluminium oxide
• What is the melting point of aluminium oxide?

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

  Cryolite
• What is the role of graphite in the electrolysis process?

  Graphite serves as the cathode and anode due to its conductivity and high melting point
• What happens to aluminium ions at the cathode during electrolysis?

  They gain three electrons to form aluminium atoms
• What happens to oxide ions at the anode during electrolysis?

  They lose two electrons to form oxygen atoms
• What does aqueous mean

  Dissolved in water
• Why must the anode be replaced regularly during electrolysis?

  Because the graphite electrodes react with oxygen to form carbon dioxide
• What are the two main reasons why producing metals by electrolysis is expensive?

  High energy requirements for melting compounds and producing electric current
• What are the steps involved in the extraction of aluminium by electrolysis?

  1. Aluminium oxide is mixed with cryolite to lower the melting point.
  2. An electric current is applied to the molten mixture.
  3. Aluminium ions are attracted to the cathode and gain electrons to form aluminium.
  4. Oxide ions are attracted to the anode and lose electrons to form oxygen.
  5. Oxygen atoms pair to form oxygen molecules.
  6. The anode must be replaced regularly due to reactions with oxygen.
• What are the key characteristics of graphite used in electrolysis?

  • Good conductor of electricity
  • High melting point
  • Used as both cathode and anode
• What is the significance of the term 'molten' in the context of aluminium oxide?

  • 'Molten' means melted, allowing ions to move freely for electrolysis.
• What is the role of cryolite in the electrolysis of aluminium?

  • Lowers the melting point of aluminium oxide, reducing energy costs.
• When is hydrogen produced at the cathode

  When the metal is more reactive than hydrogen
• If you a sulphate or nitrate compound such as copper nitrate what is produced at the anode

  Oxygen
• What is a cation

  A positive ion
• What is an anion

  Positive ion
• Electrolysis


  A process in which an electric current is used to drive a chemical reaction, typically involving the decomposition of a substance into simpler forms.
• Symbol for aqueous 


  aq
• H2 stands for

  Hydrogen gas
• What forms at the electrode if the element is below hydrogen in the reactivity series

  The metal
• Forces of attraction in ionic compounds

  The attraction between positive cations and negative anions that binds them together.
• Ionic compound in a liquid state

  The forces of attraction between ions are broken, allowing them to move freely and conduct electricity.
• Sodium chloride melts at 801°c meaning...

  It would be expensive to melt
• What compounds under go electrolysis

  Only ionic compounds
• Solid Ionic compounds cannot what?

  Conduct electricity
• What is a free electron called

  A delocalised electron