3.2 Electrolysis
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Electrolysis
The breaking down of an ionic compound using electricity
Oxidation
Loss of electrons
Reduction
Gain of electrons
Electrolyte
A liquid or solution that can conduct electricity
Cathode
Negative electrode
Anode
Positive electrode
What happens to the positive ions in molten electrolysis
The cations move to the cathode and are reduced, gaining electrons to form an uncharged substance and are discharged from the electrolyte
What happens to the negative ions in molten electrolysis
The anions move to the anode and are oxidised, losing electrons to form uncharged substances and are discharged from the electrolyte
What is the symbol for an electron in a half-equation
e-
Electrochemical cell
A circuit made up of the anode, cathode, a power source and wires connecting the two electrodes
What do you put the electrolyte in if it is a solution
A beaker
What do you put the electrolyte in if it is molten
A crucible
Why is electrolysis of an aqueous solution different to a molten substance
In a solution there are H+ and OH- ions too from the water
What forms at the cathode during electrolysis on an aqueous solution
If the positive metal ion is less reactive than hydrogen, it will be produced. If not, hydrogen is produced.
What forms at the anode during electrolysis of an aqueous solution
If a halide ion is present it will be formed. If not, oxygen and water will be formed.
When an OH- ion is oxidised at the anode, what does it form
Oxygen and water
Halide examples
-Flourine -Chlorine -Bromine -Iodine
What happens to the anode in non-inert (metal) electrode electrolysis
It loses mass
Why is mass lost at the anode during non-inert (metal) electrode electrolysis
The metal electrode loses electrons forming a metal cation which enters the solution.
What happens to the cathode during non-inert (metal) electrode electrolysis
Mass is gained
Why is mass gained at the cathode during non-inert (metal) electrode electrolysis
Electrons are gained here by metal cations in the solution reducing to form a pure metal on the electrode
How to increase the rate of electrolysis
Increase the current
How to purify copper
Electrolysis
The electrochemical cell in the purification of copper
-The anode is a lump of impure copper -The cathode is a thin piece of pure copper -The electrolyte is copper sulfate solution