Method
- First pour 50cm
of solution into a beaker - Then place plastic petri dish with two holes over beaker
- Insert an inert graphite electrode into each hole - They must not touch
- Attach crocodile leads to the electrodes and connect to a low voltage DC power supply in a series circuit
Observations and Results
Molten
- The cation (the positive metal ion) will move to the cathode (the negative electrode) where it is reduced (gains electrons) and forms atoms.
- The anion (negative non-metal ion) will move to the anode (the positive electrode) where it is oxidised (loses electrons) to form atoms.
- For elements that are only found in diatomic form, the ions will bond covalently.
- Also oxygen will react with the graphite electrodes so they will need to be replaced
Aqueous Solutions
- Aqueous solutions are dissolved in water. Water molecules ionise forming
and - At the cathode: hydrogen is produced IF the metal is MORE reactive than hydrogen otherwise the metal is produced
- At the anode: if the aqueous solution contains halide ions then the halogen will be produce at the anode otherwise oxygen is produced
Extraction
Metals that are more reactive than carbon are extracted by electrolysis
Half Equations
Half equations show what happens at the electrodes in terms of gaining/losing electrons.
For metal ions (M
For non-metal ions (M
For