Electrolytic Cell – Definition, Diagram, Working, Applications

An electrolytic cell is a electrochemical cell in which electrical energy is used to carry out chemical reaction in the cell. The chemical reaction happening inside an electrolytic cell is a redox reaction, which is spontaneous in nature. This whole process of carrying out chemical reactions with the help of electric current is called electrolysis.

In this article, we will learn in detail about electrolytic cell, its component, diagram and working. We will also learn difference between electrolytic cell and galvanic cell.

What is an Electrolytic Cell?

An electrolytic cell is an electrochemical device that uses electrical energy to start a chemical reaction. The cell consists of two electrodes (anode and cathode) immersed in an electrolyte solution. An external voltage is applied between the electrodes to drive a redox reaction at the electrode surfaces. This electric current cause the electrolyte to split into constituent ions which are mobile in nature. The ion then start moving towards electrode in the manner that anions move to anode and cations move to cathode. This lead to the deposition of element of the electrodes. This whole process is called electrolysis. Hence, we can say that an electrolytic cell is a chemical cell which operates on the principle of electrolysis.

Components of Electrolytic Cell

The three main components of an electrolytic cell are:

• Anode: A positive electrode
• Cathode: A negative electrode
• Electrolyte: A liquid solution that conducts electricity

The electrolyte solution contains dissolved ions that move around the solution, allowing it to conduct electricity. The electrolyte can be either molten or in an aqueous solution.

Diagram of Electrolytic Cell

The diagram of electrolytic cell is shown below:

Working of Electrolytic Cell

In an electrolytic cell, two electrodes are dipped into an electrolyte. When electric current is supplied to the electrolytic cell, the electrolyte breaks down into its constituent cations and anions. Now cations being positive in nature get attracted to negative diode which is cathode. The anion of the electrolyte being negative in nature get attracted to the anode which is a positive diode.

In this process, the anion at anode get lose its electron and get deposited as element. This process is called oxidation. Hence, in electrolytic cell oxidation occurs at anode.

The cation at cathode gains the electron and get deposited as metal. This process is called reduction. Hence, in electrolytic cell reduction occur at cathode.

This complete process is called electrolysis which is discussed below:

Reaction at Cathode: [Na⁺ + e^– → Na] × 2

Reaction at Anode: 2Cl^– → Cl₂ + 2e^–

Cell Reaction: 2NaCl → 2Na + Cl₂

Thus, molten sodium chloride when subjected to electric current in an electrolytic cell to generate metallic sodium and chlorine gas as the products.

Electrolytic Cell and Electrolysis

Electrolysis is a technique that uses an electric current to drive a chemical reaction that would otherwise not occur. Electrolytic cells are electrochemical cells that use an external source of electrical energy to force a chemical reaction.

The voltage needed for electrolysis to occur is called the decomposition potential. The solutions in electrolytic cells are usually either molten salt or aqueous.

Let’s consider an example of electrolysis of brine solution. In brine solution, the electrolyte is NaCl solution. When electric current is passed, NaCl breaks down into Na⁺ and Cl^– ion. The sodium ion moves to cathode and get deposited as metal ion while Cl^– get moves to anode and get deposited as element. The reaction for the process is given below:

Reaction at Cathode: [Na⁺ + e^– → Na] × 2 where, E° = –2.71 V

Reaction at Anode: 2Cl^– → Cl₂ + 2e^– where, E° = –1.36 V

Cell Reaction: 2NaCl → 2Na + Cl₂ where, E° = –4.1 V

Electrolysis is used in many industrial processes, including:

• Refining metals.
• Producing inorganic and organic products.
• Producing chlorine and caustic soda.
• Refining aluminum.

Difference Between Galvanic Cells and Electrolytic Cells

The difference between Galvanic Cell and Electrolytic Cell is tabulated below:

Galvanic Cells	Electrolytic Cell
Galvanic cells are a source of electrical energy.	Electrolytic cells require an external source of electrical energy.
Galvanic cells convert chemical energy to electrical energy.	Electrolytic cells convert electrical energy to chemical energy.
Galvanic cells have a cathode as the positive electrode and an anode as the negative electrode.	Electrolytic cells have a cathode as the negative electrode and an anode as the positive electrode.
Galvanic cells have a spontaneous reaction.	Electrolytic cells have a non-spontaneous reaction.
In a galvanic cell, the oxidation reaction takes place at anode while the reduction reaction takes place at the cathode.	In an electrolytic cell, the oxidation reaction occurs at the cathode and the reduction reaction occurs at the anode.
The two half-cells are set up in different containers, being connected through the salt bridge or porous partition.	Both the electrodes are placed in a same container in the solution of molten electrolyte.

Applications of Electrolytic Cells

The applications of electrolytic cell is given below:

Electrolytic Production of Chemicals: Electrolytic cells are used in the industrial production of various chemicals, including chlorine, sodium hydroxide, hydrogen peroxide, and aluminum. Electrochemical processes enable the conversion of raw materials into valuable chemical products through controlled electrochemical reactions.

Electroplating: Electrolytic cells can be used in electroplating, which is the process of forming a protective layer of a specific metal on another metal.

Electrolytic Capacitors: Electrolytic capacitors are electronic components that use an electrolyte as one of their conducting plates. They are widely used in electronic circuits for applications such as filtering, coupling, and energy storage due to their relatively high capacitance values and low cost.

Electrorefining: Electrolytic cells are used in the electrorefining of metals, such as copper, zinc, and aluminum, to purify them. In the electrorefining process, impure metal is dissolved into an electrolyte solution, and pure metal is deposited on the cathode while impurities settle as anode mud or remain in the electrolyte. This process helps produce high-purity metals suitable for various industrial applications.

Electrowinning: Electrolytic cells can be used in the electrowinning of metals like zinc, aluminum, copper, and lead.

Electrolysis of Water: Electrolytic cells are employed in the electrolysis of water to produce hydrogen and oxygen gases. By passing an electric current through water, it undergoes decomposition into its constituent elements: hydrogen gas is evolved at the cathode, and oxygen gas is evolved at the anode. This process is used in various applications, including hydrogen fuel production, energy storage, and industrial processes.

Conclusion

An electrolytic cell is an electrochemical cell that converts electrical energy into chemical energy. This process drives a non-spontaneous redox action. Electrolytic cells decompose chemical compounds in electrolysis. It is a process that breaks down ionic substances. Two half-cells create one electrolytic cell: reduction half-cell and oxidation half-cell.

Electrolytic cells are used in many applications such as Electrowinning, Electrorefining, Producing oxygen and hydrogen gas and Recharging batteries.

Frequently Asked Questions on Electrolytic Cell

What is meant by electrolytic cell?

Electrolytic cell is an electrochemical cell that uses electric current as external force to start an chemical reaction

What is the difference between electrolytic cell and galvanic cell?

The main difference between electrolytic cell and voltaic cell is that electrolytic cell uses current to initiate chemical reaction and voltaic cell uses chemical reaction to generate current

What are the main components of an electrolytic cell?

An electrolytic cell has three main parts: an anode, a cathode, and an electrolyte. The anode is a positive electrode while the cathode is negative.

What is the nature of electrodes in electrolytic cell?

in an electrolytic cell, the cathode is negatively charged and anode is positively charged.

What are the uses of electrolytic cells?

Electrolytic cell is mainly used to obtain element in pure form from its electrolytic solution.