SEC 4 ELECTROLYSIS REVISION

Cations move to Cathode

Anions move to Anode during electrolysis

Electrolysis always gives a metal or hydrogen at the cathode (-)

Electrolysis always gives a non-metal other than hydrogen at anode(+)

Molten ionic compound will always give metal at cathode(-) & non-metal at anode(+)

A metal or H₂ forms at cathode (-)

1. If the metal is more reactive than H₂, H₂ forms.

2. If a metal is less reactive than H_2, metal forms

A non-metal other than H₂ forms at the anode (+)

1. A concentrated solution of a halide (a chlorine, bromide, iodide) gives chlorine, bromine or iodine at the anode.

2. But if no halide is present, or halide solution is dilute, O₂ forms instead

Make sure if you are asked for observations you write about what you see, hear, smell or feel

Cations will always gain electron at cathode. Hence REDUCTION occurs

Anions will always give up electrons at anode hence OXIDATION occurs.

The idea of dissolving anode is used in electroplating and refining copper.



1. Use metal X at anode (+)

2. Use the object as the cathode (-)

3. Use a solution of a soluble compound of X as the the electrolyte