Difference Between Electroplating and Electrolysis

Electroplating vs Electrolysis
 

What is Electrolysis?

Electrolysis is a process, which uses a direct electrical current to break chemical compounds. So electrolysis process needs an external source of electrical energy for operation. A spontaneous chemical reaction is forced to do in electrolysis. For electrolysis to take place, the substance should pass electric current. Therefore, for this, electrolytic solution should be there. This contains free ions, which is produced from a substance in the molten stage or dissolved in another solvent. Oxidation-reduction reactions are taking place in electrolysis. So basically there are two electrodes called an anode and a cathode. Oppositely charged ions are attracted to the electrodes. Oxidation reaction takes place on the anode, and the reduction reaction takes place on the cathode. Electrodes are immersed in electrolyte solutions. Normally, these solutions are ionic solutions related to the type of electrode. For example, copper electrodes are immersed in copper sulfate solutions and silver electrodes are immersed in silver chloride solution. These solutions are different; hence, they have to be separated. The most common way to separate them is a salt bridge. The energy for ion movement toward the electrodes and for their reduction or oxidation is supplied by the external current supply.

Electrolysis is widely used concept and used in electrolytic cells. For an example, if we take copper and silver to be the two electrodes in the cell, silver is connected to the positive terminal of an external energy source (a battery). Copper is connected to the negative terminal. Since the negative terminal is electron rich, electrons flow from here to the copper electrode. So copper is reduced. At the silver electrode, an oxidation reaction takes place, and the released electrons are given to the electron deficient positive terminal of the battery. Following is the overall reaction taking place in an electrolytic cell, which has copper and silver electrodes.

2Ag(s)+ Cu²⁺ (aq) ⇌2 Ag⁺ (aq)+ Cu(s)

Industrially, electrolysis concept is used for producing pure state metals like Al, Mg, Ca, Na and K. Further it is used for the production of chlorine, hydrogen fuel, oxygen etc.

Electroplating

Electroplating is a plating method to coat electrodes with metal ions. The chemical basis of this process is electrolysis. Therefore, electroplating needs an external electric field to move the metal ions. Initially metals ions will be free in the solution. With the supply of electrical current, these ions will move towards the cathode and will be reduced there to produce the zero valent metal. This metal will coat the conductive electrode. Electroplating is used to increase the thickness of layers. In the jewelry industry, it is used to coat cheap products (for example products made from copper) with silver or gold. This is also used to coat metal objects with another metal. By this process, properties that the initial metal does not have can be given to it. Corrosion protection, wear resistance, lubricity are few such properties, which can be given to a metal.