The electrolysis of molten compounds
2 marks · NormalState the products formed at the electrodes when molten sodium chloride is electrolysed. For each product, name the electrode where it forms.
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Sodium forms at the cathode; chlorine forms at the anode.
Also accept: Sodium at the cathode; chlorine at the anode; Cathode: sodium; anode: chlorine
Common mistakes: Confusing which electrode each product forms at; Naming elements in the wrong order
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Marking points
B1 · 1 mark · Identifies sodium forms at the cathode
B2 · 1 mark · Identifies chlorine forms at the anode
Worked solution
When molten sodium chloride is electrolysed:
- Sodium metal forms at the cathode (negative electrode) as sodium ions gain electrons.
- Chlorine gas forms at the anode (positive electrode) as chloride ions lose electrons.
So, sodium at the cathode and chlorine at the anode.