LAB ACTIVITY CLASS VIII

COATING AN IRON KEY WITH COPPER BY ELECTROPLATING METHOD

Aim: Coating an iron key with copper by electroplating method.

Required material: Copper plate of size 2cm X 5 cm, crystals of copper sulphate (blue vitrial), a key made by iron, glass beaker, water, dilute sulphuric acid, some copper wires and battery.

Theorem : Electroplating is a process of coating a thin film of costlier or less corrodible metal on a base metal by the method of electrolysis.

Procedure :

1) Dissolve crystals of copper sulphate in pure water to prepare concentrated solution.

2) Pour the solution in a beaker and few drops of dilute sulphuric acid to it.

3) Tie one end of the copper wire to the iron object (Key) to be coated with the copper.

4) Connect its other end to the negative terminal of the battery.

5) Suspend the tied iron object into the copper sulphate solution.

6) Suspend the copper plate into the copper sulphate from positive end of the battery through a switch.

7) Put the switch on about 10 minutes.

8) Switch off the circuit and take the iron key out.

Observations :

1) The iron key get coated with a shiny, brown colour.

2) The copper particles deposited on the iron key. So the colour the key changes.

3) Copper sulphate solution has copper and sulphate ions.

4) When the electric current passes through the copper sulphate solution the free copper ions are drawn to the electrode connected to the negative terminal of the battery and deposited on it.

Result : The process of one metal coated on another metal is called electrolysis.

Precautions:

1) Care should be taken that the key and plate don’t touch each other and are a little away from one another.

2) The object to be electroplated should be free from greasy matter.

3) The surface of the article should be rough.

4) Current must be the same throughout.