1. Electrochemistry making elements using electricity
Chemistry C2 Part Five
Revision PowerPoint - Big ideas
Electrochemistry making elements using electricity

2. Electrolysis and ionic compounds
In electrolysis an electric current is passed through an ionic compound, either molten or in solution.
The compound breaks down into elements.

3. LEO the LION says GERrrr
Oxidation happens at the positive electrode. Negative ions lose electrons.
Reduction happens at the negative electrode. Positive ions gain electrons.
OXIDATION AND REDUCTION
LEO the lion says GER
Losing Electrons is Oxidation,
Gaining Electrons is Reduction.

4. Electrolysis in action
The experiment uses a direct current
The electrodes allow electrons to enter or leave the solution
The electrolyte is the ionic compound

5. Electroplating
Metal objects are electroplated by making them the negative electrode and placing them in a solution of soluble ions. e.g. nickel plating copper

6. Extracting aluminium
Aluminium is extracted by electrolysis of molten bauxite dissolved in cryolite.

7. Brine and the chlor-alkali industry
The electrolysis of brine (salt water) produces sodium hydroxide, chlorine and hydrogen.
Sodium hydroxide is used to manufacture
soaps and detergents
rayon and acetate fibres
paper
ceramics
Chlorine is used to manufacture
antiseptics and disinfectants
pesticides and weed-killers
bleach
and to kill bacteria in drinking water
Hydrogen is used to manufacture
margarine
ammonia
It is used in fuel cells and in rocket fuels for space craft

8. Electrolysis of brine
Chloride ions are discharged as chlorine gas at the +ve electrode. Hydrogen ions are discharged at the –ve electrode as hydrogen gas. Sodium and hydroxide ions are left as sodium hydroxide solution.