Electrolysis and metal extraction Flashcards
Cathode
negative - attract negative ion
Anode
Positive - attract positive
Electrolysis
Split compounds into their pure elements by using an electric current
Aqueous - What must you do for insoluble objects
Melt it to make it a liquid
Aqueous - What do you do with soluble compounds ( CuSO4 or NaCl )
Dissolve them in water to make them into an electrolyte
What ions will the water become
H plus and OH negative
Aqueous - rule for which one will be discharged at the cathode
The ion of the least reactive element will be discharged - Remember anything below copper will not be discharged
Aqueous - rule for which will be discharged at the anode
In Halide is present then they will be discharged if not the Hydroxide will get discharged ( Halide - F, Cl, Br, I, At
Equipment needed
Beaker
electrolyte - liquid solution contains an ionic compound - ions are free to move
Electrode- made of metal or carbon mainly
Wire - so electrodes can travel through
Power supply - Drive flow of electrons
Discharged
from charged ion to neutral atom
Reduced
Pb 2+ + 2e- —-> Pb
Oxidised
Bromine oxidised losing two electrons each ( 2Br - —> Br2 + 2e- )
How to reduce metal from oxide ( cheap )
Reduction with carbon - Carbon atoms displace metal oxide to form a pure metal and carbon dioxide ( 2CuO + C —> 2Cu + CO2 ) but only works for metals less reactive than carbon
Electrolysis steps ( Al2O3 )
1.) Purify
2.) Melt - very high melting point so they mix it with a mineral called cryolite which lowers the melting point
3.) Oxygen will go to Anode and will discharge their electrons (6) therefor can combine into pairs to become an oxygen molecule
4.) Electrodes will be carried though the wire to the Cathode. The cathode will have attracted the Al and would give 3 electrons to each one. The Al will slowly pool to the bottom making molten aluminium metal
Half equation - Anode - Al2O3
O2- ___ O2 + 4e-
