What do batteries and solar cells have in common? Faraday’s constant explains it all. These batteries and solar cells all involve the conversion of chemical energy into electrical energy.
Meanwhile, this process is governed by a simple but powerful equation that relates the amount of electric charge to the amount of substance involved in a reaction.
And this equation is based on a constant that bears the name of one of the greatest scientists of all time: Michael Faraday. In this blog post, you will learn about Faraday’s constant, how you can calculate it, and how you can use it to solve various problems in physical chemistry and electrochemistry.
Table of Contents
About Faraday’s Constant
Faraday’s constant is used to calculate the amount of electric charge flowing through a circuit per unit of time. This constant is equivalent to the electric charge per mole of charges (such as electrons).
One mole is the number of molecules or atoms contained in 12g of pure carbon-12. Meanwhile, this is known as Avogadro’s number (NA) and it is approximately 6.022 x 1023 atoms or molecules.
Mathematically, it is expressed as:
F = NA*e
Where:
F = Faraday’s constant
NA = Avogadro’s constant (approx. 6.022 x 1023 electrons per mole)
e = the charge of one electron (approx. 1.602 x 10-19 Coulombs)
Therefore, we can say that the Faraday constant is the charge of a single mole of electrons. This is equivalent to NA (Avogadro’s number) of electrons.
How Does Faraday’s Constant Work?
To better understand how the value of Faraday’s constant works, you must first understand how an electrolytic cell works. An electrolytic cell is often made of two electrodes submerged in an electrolyte solution.
Upon applying an electric current to electrodes, one electrode serves as a cathode while the other serves as an anode. Reduction happens at the cathode, which enables it to gain electrons. However, oxidation occurs at the anode, which makes it lose electrons.
So, the lost electrons at the anode flow through the outer circuit into the cathode, where electrons are gained. Thus, the amount of electric charge transferred through the cell is relative to the amount of substance being reduced or oxidized at the electrodes.
So, the value of Faraday’s constant relates to the quantity of electric charge passed via the cell to the quantity of substance involved in the reaction. It is represented by this equation:
Q = nF; where:
Q = the amount of electric charge passed through the cell.
n = the amount of substance involved in the reaction.
F = Faraday’s constant
Remember, the value of Faraday’s constant is 96,485.3399 Coulombs per mole of electrons. Therefore, a single mole of electrons is equal to 96,485.3399 Coulombs of electric charge.
Using this equation, you can calculate the amount of substance involved in the reaction. To do this, measure the electric charge passed through the cell and multiply it by the reciprocal of Faraday’s constant.
Faraday’s Constant Units And Derivation
The units of the Faraday constant are universally expressed in coulombs per mole (C/mol). However, the value of Faraday’s constant can be expressed in other units. The table below highlights them all.
| Value of Constant | Faraday’s Constant Units |
| 26.801 | A. h/mol |
| 23.061 | Kilo cal per volt gram equivalent |
| 96485 | Joule per volt gram equivalent |
Derivation
Since 1 mole contains 02214076 × 1023 entities and 1 Coulomb contains C/e = 1019/1.602176634 primary charges, Faraday’s constant value is given by the quotient of these:
F = NA/1/e = 9.64853321233100184×104 C⋅mol−1
Applications of Faraday’s Constant
Faraday’s constant is used in various fields like analytical chemistry, electrochemical cells, thermodynamics, and so on. We’ll discuss some of these applications here.
1. Thermodynamics
In thermodynamics, the Faraday constant is used to calculate Gibbs’ free energy of electrochemical reactions. This is essential to help you understand the thermodynamics of electrochemical systems.
2. Environmental Monitoring
Monitoring pollutants in air and water involves electrochemical sensors. Here, Faraday’s constant aids in quantifying the reactions occurring at the sensor interfaces. So, this application is pivotal in ensuring the safety of our environment and public health.
3. Electrochemistry
In electrochemistry, we use Faraday’s constant to calculate the amount of electric charge involved in chemical reactions. It’s also used to calculate a substance’s electrochemical equivalent. Meanwhile, you can use this constant to figure out the relationship between the amount of electric charge passed through an electrolytic cell and the amount of material that is dissolved or electrodeposited at the electrodes.
4. Analytical Chemistry
We use the Faraday constant in analytical chemistry in various techniques like voltammetry to calculate the amount of substance involved in an electrochemical reaction. You can also use this to determine and quantify the concentration of various species in solutions.
5. Understanding Biological Processes
The Faraday constant extends its reach into the field of biochemistry. Researchers use it to understand the electrochemical aspects of biological processes. This involves understanding cellular reactions to developing medical diagnostic tools.
6. Corrosion Protection
Industries struggling with the challenges of corrosion turn to the Faraday constant for solutions. So, by understanding the charge transfer in electrochemical corrosion reactions, engineers can design protective coatings and strategies to safeguard structures, pipelines, and infrastructure.
7. Electrochemical Cells
Again Faraday’s constant can be used in the theoretical study of electrochemical cells to calculate the potential difference between the material involved in redox reactions and the electrodes.
8. Battery Technology
You can use the constant to detect a battery’s capacity. Thus, this constant can be used to calculate the amount of charge to produce a single mole of a substance. And this is paramount in detecting the amount of energy stored in a battery.
Conclusion
In conclusion, the Faraday constant stands as a fundamental pillar in electrochemistry, revealing the relationship between charge and the mole. In this article, we’ve uncovered its significance in quantifying the flow of electrons during electrochemical reactions.
Further, this unassuming constant, named after Michael Faraday, connects atoms and molecules to measurable quantities.