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C6: electrolysis (keywords (ion= the charged particle formed when an atoms…
C6: electrolysis
keywords
ion= the charged particle formed when an atoms gains or loses electrons
electrolysis= the breakdown of a substance containing ions using electricity
cathode= electrode with a negative charge due to an excess of electrons
anode= electrode with a positive charge due to the lack of electrpns
electrolyte= a liquid containing free moving ions that can be broken down by electrolysis
anion= a negatively charged ion that is attracted to the anode
cation= a positively charged ion that is attracted to the cathode
at the anode
negative ions (anions) are attracted due to opposite charge
in aqueous solutions
group 7 ions are oxidised if present
otherwise OH- ions form oxygen molecules
at the cathode
positive ions (cations) are attracted due to opposite charge
in aqueous solutions the least reactive of H+ or metal ions are reduced to form atoms
extracting aluminium from bauxite
why?
more malleable and higher strength to weight ratio that steel- used in drinks cans, window frames, aeroplanes, cars and overhead power cables
process
step 1: purify bauxite (ore) to get alumina (Al2O3)- lots of energy used
step 2: electrolysis of molten Al2O3
cryolite is used to reduce temperature required and save energy=$
carbon electrodes react with oxygen produced to form CO2 so they need to be replaced regularly