Electrolysis Flashcards
why do compounds need to be molten before electrolysis is carried out
solid ionic compounds cannot conduct electricity-ions are not free to move, held by strong electrostatic forces
what is an electrolyte
liquid and solution forms of ionic compounds that can conduct electricity
what are electrodes made of
conducting material such as graphite
what is the negative electrode called
Cathode
what is the positive electrode called
Anode
what is meant by reduction
gaining electrons loosing o2
what is meant by oxidation
loosing electrons and gaining oxygen
in what scenario would electrolysis be used
with metals more reactive than carbon
describe the electrolysis of Aluminium oxide
Aluminium is mixed with cryolite which lowers the melting point
this therefore reduces the amount of energy needed and saves money
the molten compound contains Al3+ andO2-
Cathode Al3+ + 3e—->Al (reduction)
anode O2—–> O+2e- (oxidation)
why must the anode be replaced regularly
Bcz the oxygen molecules produced at the anode react with the graphite(carbon) forming carbon dioxide gas
why is electrolysis expensive
Melting the compounds such as aluminium oxide requires a great deal of energy
in addition lots of energy is needed to produce the electric current
what does aqueous men
dissolved in water
what do water molecules form when they ionise(split)
H+ and OH- ions
what is produced at the cathode in aqueous solutions
hydrogen is produced if the metal is more reactive than hydrogen
What is produced at the anode during the electrolysis of an aqueous solution
usually oxygen
however, if the aqueous solution contains halide ions then the halogen will be produced at the anode
