Electrolysis of salts

HideShow resource information
  • Created by: Laura
  • Created on: 16-05-13 10:00

Electrolysis of salts

When a molten salt is electrolysed ions are discharged as atoms or molecules at the electrodes.

  • Molten lead bromide
  • Anode product is bromine gas
  • Cathode product is molten lead metal

Reaction at Cathode

Pb 2+ + 2e- ----> Pb 

Reaction at Anode

2Br- ----> Br2 + 2e-

1 of 5

Electrolysis of salts

When a molten salt is electrolysed ions are discharged as atoms or molecules at the electrodes.

  • Molten lead bromide
  • Anode product is bromine gas
  • Cathode product is molten lead metal

Reaction at Cathode

Pb 2+ + 2e- ----> Pb 

Reaction at Anode

2Br- ----> Br2 + 2e-

Water ionises to a very small extent, so in an aqueous solution of a salt there are hydrogen ions and hydroxide ions as well as ions of the dissolved salt. 

2 of 5

Copper Chloride Solution

  • Cu 2+ and Cl - from the salt
  • H+ and OH- from the water

Copper loses it's charge more readily than hydrogen ions

Chloride loses it's charge more readily then hydroxide ions

Therefore:

  • Copper metal is discharged from the cathode
  • Chlorine gas is discharged from the anode
  • Leaving water
3 of 5

Copper Sulfate Solution

  • Cu2+ and SO4 2- from the salt
  • H+ and OH- from the water

Copper loses it's charge more readily than hydrogren

Hydroxide loses it's charge more readily than sulfate

Therefore:

  • Copper is the product at the cathode
  • Hydroxide ions are discharged from the anode and oxygen is produced
  • Water is also produced
4 of 5

Sodium Sulfate solution

  • Na2+ and SO4 2+ from the salt
  • H+ and OH- from the water

Hydrogen ions lose there charge more readily than sodium ions

Hydroxide ions lose there charge more readily than sulfate ions

Therefore:

  • Hydrogren gas is discharged at the cathode
  • Oxygen gas is discharged at the anode
5 of 5

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Electrolysis resources »