What are galvanic cells? Explain the working of galvanic cell with a neat sketch taking Daniel cell as example?

A galvanic cell, also known as a voltaic cell, is an electrochemical device that converts chemical energy into electrical energy. This transformation occurs through a spontaneous redox reaction, where oxidation and reduction processes take place in separate compartments called half-cells.

One common example of a galvanic cell is the Daniell cell.

The Daniell Cell

The Daniell cell is a specific type of galvanic cell that consists of two distinct half-cells connected to each other. These half-cells facilitate the redox reaction necessary for the functioning of the galvanic cell.

Structure of the Daniell Cell

• The cell is divided into two chambers within a single vessel.
• The left chamber contains an aqueous solution of zinc sulfate (ZnSO₄) and a zinc (Zn) rod submerged in it.
• The right chamber is filled with an aqueous solution of copper sulfate (CuSO₄), where a copper (Cu) rod is immersed.
• A salt bridge or porous diaphragm connects the two chambers, allowing ion exchange while preventing the direct mixing of solutions.
• The two half-cells are also connected externally by a wire through which electrons flow, driving the electrical current.

Working of the Daniell Cell

The galvanic cell operates as follows:

1. Oxidation at the Anode: In the zinc half-cell, the zinc rod undergoes oxidation, releasing electrons. The reaction is: 
   Zn → Zn2+ + 2e-
2. Reduction at the Cathode: In the copper half-cell, copper ions (Cu²⁺) from the solution gain electrons to form solid copper on the electrode. The reaction is: 
   Cu2+ + 2e- → Cu
3. Overall Cell Reaction: The net reaction for the galvanic cell is: 
   Zn + Cu2+ → Zn2+ + Cu
4. As the reactions proceed, electrons flow from the zinc electrode (anode) to the copper electrode (cathode) through the external circuit, generating electrical energy.

Representation of the Daniell Cell

A galvanic cell like the Daniell cell can be represented in shorthand notation as:

Zn | Zn2+ || Cu2+ | Cu

Importance of the Galvanic Cell

The galvanic cell is an essential concept in electrochemistry, with widespread applications in batteries, corrosion prevention, and energy storage systems. The Daniell cell, being a classic example, illustrates how chemical energy can be effectively converted into electrical energy through a redox process.

Diagram

Below is a simplified sketch of the Daniell cell, illustrating its components and working: