5. Gain and Loss of Electrons   Previous PageNext Page
       Ions and Salts

At the cathode, ions accept electrons from the external circuit and become lithium atoms, which plate out as a metal on the surface of the electrode:

At the anode, ions give up electrons to the external circuit and combine into neutral molecules, which bubble away as a gas:

Such an arrangement for passing current through a molten salt is called an electrolysis cell ("electro-lysis" meaning "breaking down with electricity").

Electrolysis is one of the best ways of preparing pure metals such as aluminum, which is electrolyzed commercially from a melt of aluminum oxide ore.


In the context of the present discussion, electrolysis cells themselves are not as important as is the essential idea that current in a molten salt is carried by the migration of positive and negative ions.

Current is carried in the same way in a solution of LiF or any other salt in water: The hydrated positive and negative ions move in opposite directions.

Salt crystals do not conduct electricity, because the ions are locked in a crystalline lattice and can not move.

Hall-Heroult cells in early aluminium production

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