Electrolysis of Molten Ionic Compounds (GCSE Chemistry)
Electrolysis of Molten Ionic Compounds
Electrodes and Half Equations
- Electrodes can be inert. Inert electrodes are sometimes used in electrolysis. The electrodes are called ‘inert� because they are unreactive. We can use inert electrodes in the electrolysis of molten lead (II) bromide.
- Carbon is used as an inert substance. The inert electrodes can be made of carbon. This is good, because carbon won’t react with the electrolyte and it also has a high melting point.
- There are rules to half equations. For molten ionic substances, there are some rules to writing half equations. In general, the metal is produced at the cathode. The non-metal is produced at the anode.
- Half equations can be written. As we’ve seen previously, we can use half equations to demonstrate the process of electrolysis.
Lead Bromide
- At the cathode, lead is formed. This appears as the silvery liquid metal underneath the remaining electrolyte.
Pb2+ + 2e–â†� Pb
- At the anode, bromine is formed. This appears as bubbles of brown gas.
2Br– – 2e– â†� Br2
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Zinc Chloride
- At the cathode, zinc is formed. This appears as metal underneath the remaining electrolyte.
Zn2+ + 2e– â†� Zn
- At the anode, chlorine is formed. This appears as bubbles of gas.
2Cl– – 2e– â†� Cl2
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