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Chemistry revision Topic 3: Electrolysis (Half equations (Pb2+ +2e-=Pb,…
Chemistry revision Topic 3: Electrolysis
Electrolytes
Ionic compounds in the molten state or dissolved in water, where electrolysis takes place
Need to be in these states so ions are free to move and can conduct elecricity
A process in which electrical energy from a direct current supply, decomposes electrolytes (breaking down a substance using electricity)
P
ositive
a
node,
N
egative
i
s
c
athode
Electrodes
A solid that conducts electricity and is submerged (underwater) in the electrolyte.
Ions move from one electrode to the other which allows the conduction through the circuit.
Positive ions (cations) will move to the cathode and will gain electrons
(reduction)
and will become atoms/molecules and are discharged from electrolyte
Negative ions (anions) will move to the anode and will lose electrons
(oxidation)
and will become atoms/molecules and are discharged from electrolyte
O
xidation
i
s
l
oss,
r
eduction
i
s
g
ain
Of molten substances:
Binary compounds are ionic compounds containing 2 ions (positive metal ion and negative non-metal ion)
Half equations
Pb2+ +2e-=Pb
2Br-=Br2 + 2e-
4OH- =O2 +2H2O +4e-
2H+ +2e_=H2
Of aqueous solutions:
Salt dissolved in water, there will be other ions
If there are hydrogen ions, metal ions won't change if they are more reactive than hydrogen as the more reactive, the more likely it is to stay
Halide ions will be formed unless there aren't any, then hydroxide ions are discharged and form oxygen and water