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what happens at anode - Electrolysis of molten Lead Bromide
2Br → Br 2 + 2e-
oxidation
bromide ions have been reduced
what happens at cathode - Electrolysis of molten Lead Bromide
(negative)
Pb2+ + 2e- → Pb
reduction
what is given off at anode - Electrolysis of molten Lead Bromide
Bromine gas (orange)
what accumulates at cathode
molten Bromine
what is electrolyte?
ionic substance (melted/in solution split by electrolysis
what are electrodes made out of, why?
made of graphite
inert so doesn’t interact with reaction
what are the two rules - electrolysis of solutions
Now we have H2O → splits to give H+ (cathode) and OH- (anode) ions
CATHODE
competition between metal hydrogen ion + hydrogen ion
MOST reactive STAYS in solution
ANODE
is there a halide/group 7 ion
yes → that halogen is formed
no → oxygen is formed
half equation for formation of oxygen at anode
4OH- → O2 + 2H2O + 4e-
CuSO4 electrolysis anode/cathode
Anode - bubbles of gas, oxygen formed
cathode - pink/brown solid coating, copper formed
H2SO4 electrolysis anode/cathode
anode - bubbles of gas, oxygen formed
cathode - bubbles of gas, hydrogen formed
NaCl
anode - bubbles of gas, chlorine formed
cathode - bubbles of gas, hydrogen formed
electrolysis - why should circuit not be connected for more than a few minutes
they may produce toxic gas e.g. chlorine
why is there a light in the electrolysis circuit
to ensure it is working
why are copper, sodium and hydrogen ions attracted to the cathode?
they are positive ions and the cathode is negative - opposite charges attract
where does the H+ and the OH- come from in the experiment
the solution that is being tested - water splits into the ions