C2b Electrolysis

Why can ionic compounds not conduct electricity when solid?

The ions are not free to move

Why can ionic compound conduct electricity when molten or aqueous?

The ions are free to move

What is an electrolyte?

An ionic compound that is aqueous or molten and so able to conduct electricity

What is a cation?

A positively charged ion

What is an anion?

A negatively charged ion

What charge is the cathode?

Negative

What charge is the anode?

Positive

What ions move towards the cathode?

Positively charged ions (cations)

What ions move towards the anode?

Negatively charged ions (anions)

Why do cations move towards the cathode?

The cathode is negatively charged and opposite charges attract

Why do anions move towards the anode?

The anode is positively charged and opposite charges attract

What is the produced at the cathode when aqueous solutions undergo electrolysis?

If the metal is more reactive than hydrogen, then hydrogen gas (H₂) is produced, if the metal is less reactive than hydrogen then the metal is produced

What is produced at the anode when aqueous solution undergo electrolysis?

If halide ions are present (group 7 ions), then the halogen is produced. If not then oxygen (O₂) is produced

What is bauxite?

Aluminium oxide (Al₂O₃)

Why is cryolite added when aluminium oxide (bauxite) undergoes electrolysis?

Lower the melting point

During the electrolysis of aluminium oxide (bauxite), why does the anode need to be regularly replaced?

Oxygen is produced at the anode, the oxygen reacts with the carbon anode to produce carbon dioxide