Sodium and oxygen can be made by passing a direct current through molten sodium oxide. The reactions at the electrodes are shown.
cathode: Na++e−→Na\mathrm{Na^{+} + e^{-} \rightarrow Na}Na++e−→Na
anode: 2O2−→O2+4e−\mathrm{2O^{2-} \rightarrow O_{2} + 4e^{-}}2O2−→O2+4e−
How many oxygen molecules form at the anode while 12 sodium atoms form at the cathode?
12
48
3
6
98 exam-style questions on OCR GCSE Chemistry 3.4 Electrolysis, covering 3.4.1 Products formed at the electrodes in electrolysis and 3.4.2 The technique of electrolysis. Each one has a worked solution and a mark scheme showing where the marks go.