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Explore the fundamental concepts of electrochemistry, including electrolysis of ionic compounds, oxidation, reduction, and applications like electroplating, aluminum extraction, and the chlor-alkali industry. Understand how electricity is used to create elements and compounds.
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Chemistry C2 Part Five Revision PowerPoint - Big ideas Electrochemistrymaking elements using electricity
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.
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.
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.