santu
Define EMF of Galvanic cell and derive expression,
for Ecell with explanation?
2
Answers
Answer:
The electromotive force of a cell or EMF of a cell is the maximum potential difference between two electrodes of a cell. It can also be defined as the net voltage between the oxidation and reduction half-reactions. The EMF of a cell is mainly used to determine whether an electrochemical cell is galvanic or not.
We shall learn more about this topic including important formulas and how to calculate the EMF of an electrochemical cell in this lesson.
What is an Electrochemical Cell?
An electrochemical cell is a device that generates electricity from a chemical reaction. Essentially, it can be defined as a device that converts chemical energy into electrical energy. A chemical reaction that involves the exchange of electrons is required for an electrochemical cell to operate. Such reactions are called redox reactions.
A cell is characterized by its voltage. A particular kind of cell generates the same voltage irrespective of the size of the cell. The only thing that depends on the cell voltage is the chemical composition of the cell, given the cell is operated at ideal conditions.
Normally, the cell voltage may be different from this ideal value, due to several factors like temperature difference, change in concentration, etc. Nernst equation formulated by Walther Nernst can be used to calculate the EMF value of a given cell, provided the standard cell potential of the cell.
Types of Electrochemical Cell
Galvanic Cell
Galvanic Cell is named after Luigi Galvani an Italian scientist. A galvanic cell is an important electrochemical cell that forms the base of many other electrochemical cells like the Daniell cell. It constitutes of two different metallic conductors called electrodes immersed in their own ionic solutions. Each of these arrangements is a half cell. Alone, a half cell is not able to generate a potential difference. But combined, they generate a potential difference. A salt bridge is used to combine the two cells chemically. It serves the required amount of electrons to the electron-deficient half cell and accepts electrons from the electron-rich half cell.