Electrolysis
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Electrolysis - facilitation of non-spontaneous reaction by electricity
Electrode material
Positive electrode: oxidising, attract -ve ions, negative electrode: reducing, attract +ve ions. If a metal is to be oxidised and consumed, such as forming copper salts from an acid (which will not react normally), it should be the positive electrode; in all other cases, where ion to be oxidised is in solution, not the electrode, carbon (from battery) or precious metal electodes should be used. Negative electrode has little usage constraint except that it does not react with any product, reactant or intermediate. For example, when producing copper salt by electrolysis, reactive anodes like lead and iron should be avoided, i.e. copper or silver is a better choice. For example, in producing sodium chromate(V) one can use chromium containing positive electrode to electrolyse sodium hydroxide, carbonate or bicarbonate, in which metallic chromium in the positive electrode is oxidised, or electrolyse dissolved sodium chromate(III) with carbon electrodes, in which chromate(III) is attracted to positive electrode and oxidised by the oxidative environment there.
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