A voltaic cell, also known as a galvanic cell, is an electrochemical device that converts chemical energy into electrical energy through a redox (reduction-oxidation) reaction. It consists of two half-cells, each containing an electrode immersed in an electrolyte solution. The two half-cells are connected by a conductive pathway, often referred to as a salt bridge or a porous separator, which allows the movement of ions between the two half-cells while preventing the mixing of the electrolytes.
In one half-cell, a oxidation reaction occurs at the electrode where electrons are released (oxidation), generating cations (positively charged ions) in the electrolyte solution. In the other half-cell, a reduction reaction takes place at the electrode where electrons are accepted (reduction), producing anions (negatively charged ions) in the electrolyte solution. This flow of electrons from the oxidation half-cell to the reduction half-cell creates an electric current through the external circuit that can be used to do work.
A common example of a voltaic cell is the Daniell cell, which consists of a zinc electrode immersed in a zinc sulfate solution in one half-cell, and a copper electrode immersed in a copper sulfate solution in the other half-cell. The zinc electrode undergoes oxidation, losing electrons and dissolving as zinc ions into the solution. These electrons flow through the external circuit to the copper electrode, where they are used for the reduction of copper ions to solid copper. This creates a flow of electric current through the circuit.
Voltaic cells are the basis of batteries and provide portable sources of electrical power. They have various applications, from powering electronic devices to supplying energy for various industrial processes.