EMF of a cell

INTRODUCTION

The Electromagnetic Field of a Cell

EMF of a cell is the maximum potential difference between two electrodes of a cell, also known as the electromotive force of a cell or EMF of a cell. The net voltage between the oxidation and reduction half-reactions can also be defined as a function of time. The electromotive force (EMF) of a cell is primarily used to determine whether or not an electrochemical cell is galvanic.

Electrochemical Cell

Essentially, an electrochemical cell is a device that creates electricity through the reaction of two chemical elements. It can be defined as a device that converts chemical energy into electrical energy, which is a simplified definition. An electrochemical cell cannot function unless there is a chemical reaction taking place that involves the exchange of electrons. Redox reactions are the term used to describe such reactions.

The voltage of a cell is what distinguishes it. A particular type of cell generates the same voltage regardless of the size of the cell used to generate it. Considering that the cell is operated under ideal conditions, the only thing that affects the voltage of the cell is the chemical composition of the battery.

Types of Electrochemical Cells

Galvanic Cell 

The Galvanic Cell was named after Luigi Galvani, an Italian scientist who pioneered the technology. A galvanic cell is an important electrochemical cell that serves as the foundation for many other electrochemical cells, such as the Daniell cell, which is described below. It is composed of two different metallic conductors known as electrodes, each of which is immersed in its own ionic solution. Each of these configurations is half a cell in size. A half cell is incapable of generating a potential difference when acting alone. However, when they are combined, they have the potential to make a difference. A salt bridge is used to chemically connect the two cells together. The electron-deficient half cell is served by it, and the electron-rich half cell is served by it. It accepts electrons from the electron-deficient half cell, and serves electrons to it.

Daniell Cell 

The Daniell cell is a modified version of the galvanic cell that is used in electronics. It is made up of zinc and copper electrodes that are immersed in zinc sulphate and copper sulphate solutions, respectively, to produce electricity. A salt bridge connects two half cells that are connected to each other. The zinc electrode serves as the anode, and the copper electrode serves as the cathode.

 When compared to the other electrode, this electrode acquires a negative potential as a result of the release of electrons from the other electrode. It is referred to as an anode.Copper, on the other hand, undergoes reduction as a result of its higher reduction potential. The copper ion in the solution of the copper half cell accepts two electrons from the electrode and transforms into copper metal, which is deposited in the electrode as a result of this reaction. This electrode is referred to as the cathode because it consumes electrons, making it a positive electrode in our classification.

The following is a representation of the anode reaction:

Zn(s) → Zn2+ (aq) + 2e–

The following is a representation of the cathode reaction:

Cu2+ (aq) +2e– → Cu(s)

The following is the combined cell reaction, also known as the overall cell reaction:

Zn(s) + Cu2+(aq) → Zn2+ (aq) + Cu(s)

Electrode potential

An electrical potential difference across an interface is created when a metal electrode is immersed in a solution containing the electrode’s own ions. The electrode potential is the difference in potential between the two electrodes.

Think about the situation in which the zinc electrode is submerged in a zinc sulphate solution. The zinc metal is oxidised in the solution by releasing two electrons, and the resulting oxidised zinc metal is dissipated. The presence of electrons in the electrode and ions in the solution results in the generation of a potential difference between them. Copper develops a positive potential in the same manner. Because of the cell potential, the combination of these two cells is effective.

This overall potential is equal to the difference between the potentials of the two half cells added together. The standard hydrogen electrode (SHE) is an example of a half cell that follows a standard design. When SHE is turned on, the potential value is automatically set to zero volts. The potential difference between the standard hydrogen electrode and an unknown half cell is measured using the standard hydrogen electrode. The potential difference of the unknown half cell will be the measured value because SHE has a voltage of zero volts.

The Electrochemical Series 

Similarly, by calculating the standard potential values of various metals and arranging them in increasing order of potential, we can obtain the electrochemical series.

The determination of cell potential is impossible without the use of electrochemical series. Moreover, it assists in the selection of electrode metals for use in the construction of a cell.

The electrochemical series table depicts the arrangement of a few elements in ascending order of their reduction potentials, as indicated by the arrows. Lithium typically has the lowest reduction potential, while fluorine typically has the highest. Hydrogen has a zero reduction potential when combined with oxygen. This is due to the fact that all other elements are compared to hydrogen in order to determine their standard electrode potential.

Representation of  electrochemical cell 

It is possible to represent an electrochemical cell with the help of special notations. This is useful in determining the composition of the cell as well as the quantity of the constituents.

The Daniell cell described above can be represented in the following ways:

Zn | Zn2+ (1M) || Cu2+ (1M) | Cu

Lets break it down and understand its components:-

The anode is represented on the left-hand side of the notation. A set of two electrons per zinc atom is released at the anode, which results in the conversion of Zn to the cathode. Because the solution used has a concentration of 1M, we have included it in the representation as well.

Zn | Zn2+ (1M)

The cathode is located on the right side of the circuit. This occurs when an electron pair from the electrode is absorbed by the electrolyte, which results in the conversion of the copper to metal. We’re using the same 1M copper sulphate solution that we did before.

Cu2+ (1M) | Cu

By utilising a salt bridge, these two half-cells are joined together. The two vertical bars on either side of the salt bridge represent the bridge itself.

Zn | Zn2+ (1M) || Cu2+ (1M) | Cu

Finding the Cell Potential of an Electrochemical Cell 

The electrochemical cell’s cell potential or electromotive force (EMF) can be calculated by summing the electrode potentials of the two half-cells. There are typically three methods that can be used for the calculation: arithmetic, geometric, and graphical.

• By taking the oxidation potential of the anode and the reduction potential of the cathode into consideration.
• By taking the reduction potentials of both electrodes into consideration.
• We can do this by calculating the oxidation potential of both electrodes.

It is possible to calculate the standard cell potential (∆E°) of a galvanic cell by taking into account the standard reduction potentials of the two half cells, which are E°.

CONCLUSION

The Electromagnetic Field of a Cell

EMF of a cell is the maximum potential difference between two electrodes of a cell, also known as the electromotive force of a cell or EMF of a cell. The net voltage between the oxidation and reduction half-reactions can also be defined as a function of time. An electrochemical cell is a device that creates electricity through the reaction of two chemical elements. It can be defined as a device that converts chemical energy into electrical energy, which is a simplified definition.An electrical potential difference across an interface is created when a metal electrode is immersed in a solution containing the electrode’s own ions. The electrode potential is the difference in potential between the two electrodes.The electrochemical cell’s cell potential or electromotive force (EMF) can be calculated by summing the electrode potentials of the two half-cells.