5.ELECTROLYTIC AND CHEMICAL CELL..

D : Analysing
redox
reactions in
electrolytic
and chemical
cells

Electrolysis of Copper(II) Sulphate Solution
using Carbon Electrodes

• Ions present:

From copper(II) cations anions
sulphate Cu2+(aq) SO42-(aq)
H+(aq) OH-(aq)
From water

Electrolysis of Copper(II) Sulphate Solution
using Carbon Electrodes

Anode : 4OH-  O2 + 2H2O + 4e

Oxidation ; release electron ;
oxidation number of oxygen
increases from -2 to 0

Electrolysis of Copper(II) Sulphate Solution
using Carbon Electrodes

Cathode : Cu2+ +2e Cu

Reduction ; receive electron ;
oxidation number of copper(II)
ion decreases from +2 to 0

Zn Zn2+ + 2e K
Na
Zn is-ve terminal Ca
Zn is more electropositive Mg
Al
than Cu Zn
Fe
Zn is anode Sn
Zn undergoes oxidation Pb
H
Cu
Ag
Au

Copper(II) Cu2+ + 2e  Cu
sulphate
solution Cu is +ve terminal
Cu is less electropositive than

Zn

Cu is cathode
Cu2+ undergoes reduction

Require Does not
electric require
current electric
current

.Electrodes: Differences . Electrodes :
same 2 different
metal or Chemical
carbon energy  metals
electrical
Electrical
energy  energy
chemical

energy

Oxidation : Reduction :
Occurs at occurs at
positive positive
electrode electrode

. Similarities: .

Oxidation at
anode

Reduction at
cathode

Reduction: Oxidation:

Occurs at Occurs at
negative negative
electrode electrode

Nickel-cadmium . Dry cell
cell

Chemical .
cell
Alkaline cell
Lead-acid
acumulator cell . Mercury cell

.

By Azlina Awang