A galvanic cell is a device that converts chemical energy into electrical energy. A galvanic cell generates an electric current due to the redox reaction which is occurring inside it. Daniell cell, dry cell, leclanche cell, etc are examples of galvanic cells.
Construction of Galvanic Cell
A galvanic cell can be constructed by uniting an oxidation electrode with a suitable reduction electrode. The solutions involved in the two electrodes can be made in communication with each other either by direct contact through a porous diaphragm or through a salt bridge.
Functions of Salt Bridge
- It maintains the electrical utility of half cells.
- It completes the circuit by allowing the flow of electron.
- Minimises and liquid-liquid junction potential.
In the outer circuit, the two electrodes are connected to a device that is capable of utilizing the electrical energy produced.
A salt bridge is U shaped glass tube filled with the concentrated solution of an inert electrolyte such as KCl, kNO3, K2SO4, etc. It completes the electrical circuit by allowing the ions to flow from one-half cell to another half cell and maintains the electrical utility of the solutions present in the two half cells.
In a galvanic cell, the electrode at which the oxidation process occurs is called the anode whether the point at which the reduction process takes place is called the cathode.
it is to be noted that the anode is of negative polarity while the cathode is of positive polarity in a galvanic cell.
Representation of Galvanic Cell
A galvanic cell is always represented by writing an oxidation electrode at the left and the reduction electrode at the right. Direct contact of the two solutions is represented by a vertical line while the contact of the two solutions through a solve it is shown by two parallel vertical lines. For example, involving a salt bridge is represented as given below
EMF (Electromotive Force) of a galvanic cell is due to a redox reaction. It can be obtained by adding oxidation and reduction reactions in such a way that electrons get canceled. For example, does cell reaction of a Daniel cell can be obtained as follows
EMF of a Galvanic Cell
The electromotive force of a galvanic cell is defined as the difference of electric potential which causes the flow of current from one electrode to another with virtually no current is drawn from the cell. According to the IUPAC convention, the EMF of the cell is obtained by