Chemistry C2

• Electrolysis is the passage of electricity to cause a chemical reaction
• Only IONIC SUBSTANCES can undergo electrolysis
• Ionic susbstances must be either MOLTEN or DISSOLVED IN AQUEOUS SOLUTION for electrolysis to occur
• Positive ions (cations) - are attracted to the negative electrode (cathode) where they GAIN electrons
• Negative ions (anions) - are attracted to the positive electrode (anode) where they LOOSE electrons
• Oxidation is loss OIL
• Reduction is gain RIG

e.g - Electrolysis of sodium chloride to give hydrogen, chlorine and sodium hydroxide

- Electrolysis of aluminium oxide to give aluminium and oxygen

- Purification of copper by making the impure copper the anode and collecting pure copper in the cathode.