Elctrolysis

Electrolytes

Molten or aqueous ionic compounds that can now conduct electricity

Negative electrode

Cathode, attached to negative terminal of power pack

Positive electrode

Anode, connected to positive terminal of power pack

Positive ions…

Are attracted to the negative electrode, the cathode, and gain electrons (reduction reaction)

Negative ions are…

Attracted ro the positive electrode, the anode, and they lose electrons (they are oxidised)

Why is aluminium mixed with cryolite

It lowers the melting point, less energy needed for it to melt

Why is graphite used to make the electrodes

It is a good conductor of electricity, it has a high melting point, can withstand high temperatures

When oxide ions are oxidised, anodes that are made of graphite need to be replaced because…

Carbon dioxide is produced, which is a greenhouse gas

Why is electrolysis expensive?

• Melting compounds are expensive as it requires great deal of energy

• Lots of energy is also needed to produce electric current

When an aqueous solution is used, hydrogen is produced at the cathode if…

The metal is more reactive than hydrogen

What is often used to make inert electrodes

Platinum

What happens to water when aqueous solutions are used?

Water molecules ionise and split into H+ ions and OH- ions

If an aqueous solution contains halide ions…

The halogen will be produced at the anode