Electrolysis

What is the substance broken down by electrolysis called?

The electrolyte

What is an electrode?

Conducting rod

What does the term electrolysis mean?

The breaking down of a substance containing ions using electricity.

What happens in electrolysis?

Positive ions move to the negative electrode (cathode) whilst negative ions move to the positive electrode (anode). Ionic compounds can only be electrolysed when molten or in solution.

P ositive

A node

N egative

I s

C athode

What happens to positive ions during electrolysis?

They gain electrons at the cathode and are REDUCED

What happens to negative ions during electrolysis?

They lose electrons at the anode and are OXIDISED. They are released as a gas.

Why does the electrolyte have to be molten or in solution?

Their ions are then free to move to the electrode.

Metal ions will always have a 

POSITIVE

charge

O xidation

I s

L oss                          of electrons

R eduction

I s

G ain                          of electrons

If two ions go to the same electrode which one will be produced?

When electrolysis happens in solution the less reactive element between hydrogen (from the water) and the metal is usually produced at the cathode. At the anode we usually get oxygen gas.

Uses of chlorine

We can react chlorine with sodium hydroxide in the electrolysis of brine. Making a solution of bleach - used for killing bacteria.

Plastics such as PVC.

Uses of hydrogen

Hydrogen we make by electrolyising brine is pure. Useful for the food industry > we make margarine by reacting hydrogen with vegetable oils.

AN   OX

ANode OXidation

RED   CAT

CAThode REDuction