Galvanic cell
Introduction
A Galvanic cell, also known as a voltaic cell, is a device in which a redox reaction spontaneously occurs and produces an electric current. It is named after Luigi Galvani and Alessandro Volta, who both made significant contributions to the field of electrochemistry.
Structure of a Galvanic Cell
A typical galvanic cell consists of two half-cells. Each half-cell contains an electrode and an electrolyte. The electrode, which can be a metal or a non-metal, is immersed in the electrolyte, a solution that contains ions. The two half-cells are connected through a salt bridge or a porous disk.
Electrodes
In a galvanic cell, the electrodes serve as sites where the oxidation and reduction half-reactions occur. The electrode at which oxidation occurs is called the anode, while the electrode at which reduction occurs is called the cathode. The anode and cathode are often made of different materials, which are chosen based on the specific redox reaction that is to occur in the cell.
Electrolytes
The electrolytes in a galvanic cell are solutions that contain ions. These ions can originate from a variety of sources, such as salts, acids, or bases. The role of the electrolyte is to facilitate the movement of ions between the anode and cathode, which is essential for the redox reaction to occur.
Salt Bridge
The salt bridge or porous disk in a galvanic cell serves to maintain electrical neutrality within the internal circuit. It allows the flow of ions from one half-cell to the other, balancing the charge and allowing the redox reaction to continue. The salt bridge is often a U-shaped tube filled with a salt solution, while a porous disk is a solid material that allows ions to pass through.
Redox Reaction
The redox reaction in a galvanic cell involves the transfer of electrons from the anode to the cathode. This transfer of electrons is what generates the electric current. The overall reaction is the sum of the oxidation half-reaction at the anode and the reduction half-reaction at the cathode.
Applications of Galvanic Cells
Galvanic cells have a wide range of applications, from powering small devices like watches and calculators to larger applications like car batteries. They are also used in electroplating, where a thin layer of metal is deposited onto a surface, and in corrosion prevention.