4.4.3.1 The process of electrolysis

Electrolysis of lead bromide

PbBr₂

Pb²⁺

2Br⁻

Pb→ Pb²⁺ + 2e⁻

2Br + 2e⁻ —> 2Br⁻

Why solid ionic compounds cannot conduct electricity

The ions are locked in place and are not free to move

There are strong electrostatic attraction

What happens when ionic compounds are melted or dissolved in water

The forces of attraction are Brocken and the ions are free to move

These liquids and solutions can now conduction electricity

The metal is produced at

Cathode

The non-metal is produced

At anode

Equipment used in electrolysis

Beaker containing electrolyte Electrodes (left cathode, right anode) Wire: electrons can flow Power supply (drive flow of electrons)

Electrolyte

Liquid or solution containing an ionic compound where the ions are free to move

If compound soluble

Dissolve in water

If compound insoluble

Melt it to obtain molten liquid Only way to ensure ions are free to move

Electrodes

Solid conductors: made of metal or carbon

Electrolysis

Splitting of substances using electricity

Process of electrolysis

Negative ions attracted to positively anode When they get there they will be discharged (go from charged ions to neutral atom) From anode gas is usually discharged Positive ions attracted to negative cathode When they get there, they will be discharged (to form a pure metal → metal will fall to bottom and form a layer of molten metal

Oxidation and reduction

Ions are being oxidised and reduced at electrodes At cathode→ reduced At anode→ oxidised

Overall process of electrolysis

Electrons from anions is being passed to anode them being transported along the wire to the cathode using power of battery These electrons are given to the cations to become neutral Using electricity to convert that ions in a compound back into their pure elemental form by transferring the electrons from the negative ions to the positive ions

Ionic compounds

Solid ionic compounds cannot conduct electricity The ions are arranged in a giant lattice with strong electrostatic forces of attraction Ions are not free to move When melted or dissolved in water, the forces of attraction are broken and the ions are free to move These liquids and solutions can now conduct electricity These liquids are called electrolytes

Molten

Melted