Introduction:

In Class 11 Chemistry, the concept of Electrolytic Cells and Electrolysis is one of the most important topics under the chapter Electrochemistry. Electrolysis has vast applications in industries such as metal extraction, purification, and electroplating. Understanding how electrolytic cells work helps students build strong foundations for exams like NEET, JEE, and Board examinations.



Electrolytic Cell: Definition and Working

An electrolytic cell is a device that uses electrical energy to bring about a non-spontaneous chemical reaction. Unlike a galvanic cell, where chemical energy is converted to electrical energy, an electrolytic cell works in the reverse direction.

Structure of Electrolytic Cell:

1. Electrolyte – A substance (molten salt or aqueous solution) that allows ions to move freely.

2. Electrodes – Two conductors (anode and cathode) dipped in the electrolyte.

  - Anode (positive terminal) – oxidation occurs.

  - Cathode (negative terminal) – reduction occurs.

3. External Source – A battery or DC source provides electrical energy.

Example: Electrolysis of molten NaCl gives sodium at the cathode and chlorine gas at the anode.

Read Also: Experiments of Faraday and Henry: Class 12 Physics Notes

Electrolysis: Meaning and Process:

Electrolysis is the process of using electrical energy to decompose an electrolyte into its constituent ions.

Steps Involved:

1. Ionization of Electrolyte – Electrolyte dissociates into positive and negative ions.

2. Migration of Ions – Positive ions (cations) move to the cathode, and negative ions (anions) move to the anode.

3. Electrode Reactions –

  - At Cathode: Cations gain electrons (reduction).

  - At Anode: Anions lose electrons (oxidation).

Faraday’s Laws of Electrolysis (Class 11 Important Topic)

1. First Law: The mass of a substance deposited at an electrode is directly proportional to the quantity of electricity passed.

  m ∝ Q, where Q = I × t (Current × Time).

2. Second Law: When the same amount of electricity is passed through different electrolytes, the mass of substances deposited is proportional to their equivalent masses.

Applications of Electrolysis:

Electrolysis has wide applications in everyday life and industries:

- Electroplating: Coating one metal with another (e.g., gold plating on ornaments).

- Metal Extraction: Aluminium, sodium, magnesium obtained through electrolysis.

- Purification of Metals: Copper, zinc purified by electrolytic refining.

- Electrolytic Production: Hydrogen, chlorine, sodium hydroxide, etc.

Difference between Electrolytic Cell and Galvanic Cell:

Conclusion:

Electrolytic cells and electrolysis form the backbone of industrial chemistry and practical applications in daily life. From metal refining to electroplating, their principles are applied everywhere. For Class 11 Chemistry, a strong understanding of these concepts, including Faraday’s laws and differences with galvanic cells, is essential for scoring well in competitive exams like NEET and JEE.