Principle of Electrolysis of Copper Sulfate Electrolyte

Electrolysis

Before understanding the principle of electrolysis, we should know what is electrolyte or definition of electrolyte

Definition of Electrolyte

An electrolyte is such a chemical that's atoms are normally closely bonded together but when it is dissolved in water, its molecules split up into positive and negative ions. The positively charged ions are referred as cations whereas negatively charged ions are referred as anions. Both cations and anions move freely in the solution.

Principle of Electrolysis

As discussed in the definition of electrolyte, whenever any electrolyte gets dissolved in water, its molecules split into cations and anions moving freely in the electrolytic solution. Now two metal rods are immersed in the solution and an electrical potential difference applied between the rods externally preferably by a battery . These partly immersed rods are technically referred as electrodes. The electrode connected with negative terminal of the battery is known as cathode and the electrode connected with positive terminal of the battery is known as anode. The freely moving positively charged cations are attracted by cathode and negatively charged anions are attracted by anode. In cathode, the positive cations take electrons from negative cathode and in anode, negative anions give electrons to the positive anode. For continually taking and giving electrons in cathode and anode respectively, there must be flow of electrons in the external circuit of the electrolytic. That means, current continues to circulate around the closed loop created by battery , electrolytic and electrodes. This is the most basic principle of electrolysis.

Electrolysis of Copper Sulfate

Whenever copper sulfate or CuSO₄ is added to water, it gets dissolved in the water. As the CuSO₄ is an electrolyte, it splits into Cu^{+ +} (cation) and SO₄ ^{− −} (anion) ions and move freely in the solution. Now if two copper electrodes are immersed in that solution, the Cu^{+ +} ions (cation) will be attracted towards cathode i.e. the electrode connected to the negative terminal of the battery . On reaching on the cathode, each Cu^{+ +} ion will take electrons from it and becomes neutral copper atoms. Similarly the SO₄ ^{− −} (anion) ions will be attracted by anode i.e. the electrode connected to the positive terminal of the battery . So SO₄ ^{− −} ions will move towards anode where they give up two electrons and become SO₄ radical but since SO₄ radical can not exist in the electrical neutral state, it will attack copper anode and will form copper sulfate. If during electrolysis of copper sulfate, we use carbon electrode instead of copper or other metal electrodes, then electrolysis reactions will be little bit different. Actually SO₄ can not react with carbon and in this case the SO₄ will react with water of the solution and will form sulfuric acid and liberate oxygen.



The process described above is known as electrolysis. In the above process, after taking electrons the neutral copper atoms get deposited on the cathode. At the same time, SO₄ reacts with copper anode and becomes CuSO₄ but in water it can not exist as single molecules instead of that CuSO₄ will split into Cu^{+ +}, SO₄ ^{− −} and dissolve in water. So it can be concluded that, during electrolysis of copper sulfate with copper electrodes, copper is deposited on cathode and same amount of copper is removed from anode.

Video Presentation of Basic Principle of Electrolysis