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Electrolysis of Solutions

Rules of Electrolysis:* Learn the reactivity seriesAt the inert Cathode ( - )

Either Hydrogen OR the metal is discharged.

Only metals less reactive than Hydrogen will be discharged.

If the metal ion in solution is more reactive than Hydrogen then hydrogen is discharged.

At the inert Anode ( + )

Halide ions are discharged in concentrated halide solutions ( halides = Cl, Br, I )

In dilute halide solutions oxygen gas is discharged

Sulphate and nitrate ions are never discharged. These ions produce oxygen gas

Try the worksheet below: write the ions discharged at each electrode.

The electrolysis of a molten ionic compound ALWAYS gives:

- the metal at the cathode and a- non metal at the anode

For example:

Ionic Conductors are never solids!

Remember for an electric current to flow (in liquids) there must be free ions! Solid ionic compounds do not conduct electricity. Only ionic compounds that are molten or in solution will conduct electricity.