What Is a Galvanic Cell?
A galvanic cell, also known as a voltaic cell, is a type of electrochemical cell that converts chemical energy into electrical energy through a spontaneous redox (oxidation-reduction) reaction. In simple terms, it's a device that uses a chemical reaction to create an electric current. Common batteries are practical examples of galvanic cells.
Section 2: Key Components
A galvanic cell consists of two half-cells connected by a salt bridge and an external wire. Each half-cell contains an electrode (a metal strip) submerged in an electrolyte solution. The anode is the electrode where oxidation occurs (loss of electrons) and is considered the negative terminal. The cathode is the electrode where reduction occurs (gain of electrons) and is the positive terminal.
Section 3: A Practical Example (Daniell Cell)
A classic example is the Daniell cell. One half-cell has a zinc electrode in a zinc sulfate solution, and the other has a copper electrode in a copper sulfate solution. Zinc is more reactive, so it acts as the anode, oxidizing to form zinc ions (Zn → Zn²⁺ + 2e⁻). The released electrons travel through the external wire to the copper cathode, where copper ions are reduced to solid copper (Cu²⁺ + 2e⁻ → Cu). The salt bridge allows ions to flow and maintain charge balance, completing the circuit.
Section 4: Importance and Applications
The primary importance of galvanic cells lies in their ability to function as portable power sources. They are the fundamental principle behind all non-rechargeable and rechargeable batteries. From the small batteries in watches and remote controls to the larger batteries in cars and laptops, galvanic cells provide a convenient way to harness the energy stored in chemical bonds to power our devices.