Electrolysis

• Molten ionic compounds (preparation)

  • melted/dissolved into water
  • Forces of attraction are broken and ions are free to move
  • Solution can now conduct electricity
• Molten ionic compound

  • positive ions gain electrons (reduction) at cathode
  • Negative ions lose electrons (oxidation) at anode
• Aqueous

  • Cathode- hydrogen produced if metal is more reactive than hydrogen, Less reactive metal of hydrogen will be formed as pure
  • Anode- Halide ions will form, if no halide ions present oxygen will be formed from hydroxide ions
• Electroplating

  • negatively charged cathode is plated
  • Positively charged anode is plating
  • electrolyte contains ions for plating metal
• Purifying copper

  • Cathode is pure copper
  • anode is impure copper, produced form copper ore
  • electrolyte is copper (II) sulphate solution
  • at anode: Cu2+ (aq) + 2e- --> Cu (s)
  • At cathode: Cu (s) --> Cu2+ + 2e-
• Non-inert electrode

  • can decompose in electrolyte
  • Copper electrodes
  • Mass of anode will decrease ands mass of cathode will increase