Presentation on theme: "Chemistry C2 Part Five Revision PowerPoint - Big ideas Electrochemistry making elements using electricity."— Presentation transcript:
Chemistry C2 Part Five Revision PowerPoint - Big ideas Electrochemistry making elements using electricity
Electrolysis and ionic compounds In electrolysis an electric current is passed through an ionic compound, either molten or in solution. elements The compound breaks down into elements.
LEO the LION says GERr r r 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.
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
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
Extracting aluminium Aluminium is extracted by electrolysis of molten bauxite dissolved in cryolite.
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
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.