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Electrolytes
Molten or aqueous ionic compounds that can now conduct electricity
Negative electrode
Cathode, attached to negative terminal of power pack
Positive electrode
Anode, connected to positive terminal of power pack
Positive ions…
Are attracted to the negative electrode, the cathode, and gain electrons (reduction reaction)
Negative ions are…
Attracted ro the positive electrode, the anode, and they lose electrons (they are oxidised)
Why is aluminium mixed with cryolite
It lowers the melting point, less energy needed for it to melt
Why is graphite used to make the electrodes
It is a good conductor of electricity, it has a high melting point, can withstand high temperatures
When oxide ions are oxidised, anodes that are made of graphite need to be replaced because…
Carbon dioxide is produced, which is a greenhouse gas
Why is electrolysis expensive?
Melting compounds are expensive as it requires great deal of energy
Lots of energy is also needed to produce electric current
When an aqueous solution is used, hydrogen is produced at the cathode if…
The metal is more reactive than hydrogen
What is often used to make inert electrodes
Platinum
What happens to water when aqueous solutions are used?
Water molecules ionise and split into H+ ions and OH- ions
If an aqueous solution contains halide ions…
The halogen will be produced at the anode
Note 
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