C6 - Electrolysis


C6.1 - Intro

  • breaks down substance using electricity
  • Ionic compounds can only be electrolyised when in molten or water due to their ions being free to move and carry charge to electorodes.
  • Panic - Positive anode, Negative is cathode
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C6.2 - changes at the electrodes.

  • Ions move to opisiteley charged electorde. 
  • Cathode - positive ions gain electrons, so are reduced
  • Anode - negative ions lose electrons, so are oxidised. 
  • Less reactive element is produced at Cathode
  • At anode: 
  • oxygen given off from discharged hydroxide ions
  • a halogen produced if a soloution of halide
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C6.3 - extraction of alluminium.

  • Alumminium oxide - from bauxite, is electrolyised in extraction.
  • aluminium oxide mixed with molten cryolite to lower melting point, reducing energy.
  • Aluminium forms at cathode
  • oxygen forms at anode
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C6.4 - Electrolysis of aqueous soloutions.

  • Sodium Chloride soloution (Brine) when electrolysed - Chlorine gas, hydrogen gas given off at electrodes, sodium hydroxide in soloution.
  • Hydrogen produced at Cathode as H+ ions are discharged from soloution in prefrence to Na- ions.
  • Chlorine produced at anode as Cl- ions are discharged in prefrence to OH- ions.
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C6 - Electrolysis

C6 - Electrolysis.

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