C6 - Electrolysis

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  • C6 - Electrolysis
    • C6.4 - Electrolysis of aqueous solutions
      • Chlorine is produced at the anode as Cl- ions are discharged from solitionin preference to OH- ions
      • When you electrolyse sodium chloride solution, you get 3 products: Chlorine gas, Hydrogen & Sodium hydroxied left  in the solution
      • H is produced at the cathode as H+ ions are duscharged frin solution in preference to Na+
    • C6.3 - The extraction of aluminium
      • In electrolysis, the ions move towards the oppositely charged electrodes
      • At the anode, negative ions lose their extra electrons, so are oxidised
      • At the Cathode, positive ions gain electrons so are reduced.
      • when electrolysis happens in an aqueus solutioj, the less reactive element is usually produced at the cathode. At the anode either: oxygen is given off or a halogen is produced
    • C6.2 - Changes at the electrodes
      • Aluminiyn forms at the at the cathode and oxygen forms at the anode
      • The aluminium oxide is mixed with molten Cryolite to  lower its melting point, reducing the energy needed to extract the aluminium
      • The carbon anodes are replaced regularly as they gradually burn away as the oxygen reacts with the hot carbon anodes, forming C02 gas
      • Aluminium oxide, from the ore bauxite, is electrolysed in the  extraction of aluminium metal
    • C6.1 - Introduction to electrolysis
      • Electrolysis breaks down a substance using electricity
      • Ionic compounds can onlyu be electrolysised when they are molten or dissolbed in water. This is because their ions are then free to move and carry theor carge to the electrodes
      • In electrolysis, positive ions move to the cathode while negative ions move to the anode.


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