Electrolysis

When an electric current passes through certain compounds in Solutions or molten state, they are decomposed. They compounds are called electrolytes and their decomposition by an electric current are called electrolysis. The vessel containing the electrolyte is called a voltammeter. The electrode by which the current enters into the electrolyte is called the anode. The electrode by which the current leaves the electrolyte is called the cathode. Anions carry –ve charge and move towards the anode. Cations carry +ve charge and move towards the cathode. For this reason anions are said to be electro-negative and cations are said to be electro-positive in character. In general, all metals and hydrogen are electro-positive and all non-metals are electro-negative.

Copper Voltammeter. A copper voltammeter consists of a glass vessel containing copper sulphate solution and two copper electrodes. When a steady current is passed through the copper sulphate solution, it dissociates into Cu++ and So4 – ions, copper is deposited on the cathode and is removed from anode.
 

Water Voltammeter. It consists of a glass vessel, at the base of which two electrodes are provided. The vessel contains acidic water. Two long tubes filled with acidic water were held in inverted position over the two electrodes. When current is passed through the acidic water, hydrogen gas is collected in the inverted tube put over cathode and oxygen gas is collected in the tube placed over anode.


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