Electrolysis of molten compounds

Similar experiments were performed on other substances which until then had been thought of as elements. Soda (sodium hydroxide) was melted and had electricity passed through it it split up into sodium and oxygen. 

An electrolyte is a substance which, when molten or in solution, conducts electricity and is broken up while doing so. 

During electrolysis, the positive (usually metal) ions travel to the cathode the negative ions travel to the anode. When they reach the electrodes, the ions are discharged, i.e. they lose their charge. The negative ions give electrons away and become neutral the positive ions take in electrons and become neutral. 

In this process the lead ions have gained electrons they have been reduced (remember OILRIG - see Section 2.5.1). 

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Several elements are produced commercially by electrolysis. In Sections 21-3 to 21-5, we described some electrolytic cells that produce sodium (the Downs cell), chlorine, hydrogen, and oxygen. Electrolysis of molten compounds is also the common method of obtaining other Group lA metals, HA metals (except barium), and aluminum (Section 22-3). Impure metals can also be refined electrolytically, as we will describe for copper in Section 22-8. 

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