Predicting Products Of Electrolysis

Question 1

Can an ionic solid be electrolysed?

Answer 1

No as the ions are fixed position and can’t move

But molten can as the ions can freely move

Question 2

What happen to positive and negative ions at the electrodes?

Answer 2

Positive metal ions are reduced to metal atoms at cathode

Negative ions are oxidised to atoms to molecules at the anode

Question 3

Give an example of half equations and positive metal and negative ions:
(lead and bromide)

Answer 3

Cathode- Pb2+ + 2e- ->Pb

Anode 2Br- -> Br2 + 2e-

Question 4

What happens at the electrolysis of an aqueous solution?

Answer 4

In aqueous solutions there is hydrogen and hydroxide ions form the water.
At cathode if hydrogen ions and metal ions are there hydrogen gas will be made but, if the metal is more reactive then hydrogen then solid metal will be made
At the anode If hydroxide and halide ions are present then molecules of chlorine bromine or iodine will be formed. If no halide ions are present then oxygen will be made.

Question 5

What happens to copper chloride? Aqueous?

Answer 5

Copper will be at the cathode
Cathode half equation : Cu2+ + 2e- -> Cu

Chlorine at the anode
Anode half equation : 2Cl- -> Cl2 + 2e-

Question 6

What happens to sodium Sulfate? Aqueous?

Answer 6

Hydrogen at cathode
Half equation : 2H+ + 2e- -> H2

Oxygen at anode
Half equation : 4OH- -> O2 + 2H2O + 4e-

Question 7

What happens to water acidified with sulphuric acid? Aqueous?

Answer 7

Hydrogen at cathode
Half equation : 2H+ + 2e- -> H2

Oxygen at anode
Half equation : 4OH- -> 2H2O + O2 + 4e-

Question 8

What products does OH- produce at the anode?

Answer 8

Water and oxygen