Boltzmann constant


In the area of ​​science, we find many important definitions related to the area of physics . One of them is the physical constant , which represents the value of a physical quantity whose value is fixed in a certain system of units and which invariably prevails during physical processes over time. There are many physical constants, one of them is known as Boltzmann’s constant .


What is Boltzmann’s constant?

Boltzmann’s constant is a constant that is responsible for relating the temperature with energy and also studied the heat with the relationship it has with other types different from energy .

  • Characteristics of the Boltzmann constant
  • What is the Boltzmann constant for
  • History
  • Value
  • Importance of the Boltzmann constant

Characteristics of the Boltzmann constant

The main characteristics of Boltzmann’s constant are the following:

  • It is considered as a proportionality factor that occurs between the temperature measured in units and units of energy.
  • Its value in the SI is K = 1,38064852 (79) x 10 -23 J / K = 1,3806504 x 10 -16 ergs / K.
  • It is a constant that occurs between ideal gases .
  • Express the relationship between the average energy of a particle and its temperature
  • The constant is used in equations to describe the properties that gases have .
  • Boltzmann’s constant is expressed in joules per kelvin .
  • Boltzmann’s constant appears in many ways , especially in sub – disciplines of physics of thermodynamics and statistical mechanics.
  • Boltzmann’s constant counts individual molecules rather than the number of moles.

What is the Boltzmann constant for

Boltzmann’s constant has many uses. Boltzmann’s constant is closely related to the constant ideal gas, since both are useful for the ideal gas law to determine the relationship between the pressure , the volume and the number of molecules of gas and temperature. One of them is in the area of statistical mechanics and is used to convert from the theoretical version of entropy information to thermodynamic entropy . It is also useful in the equation for entropy in order to provide a more mathematical explanation of it.


Developed during the 1860s and 1870s by physicists Ludwig Boltzmann and James Clerk Maxwell . Although Boltzmann was able to link entropy and probability for the first time in 1877, this relationship was never expressed by means of a more specific constant until Max Planck was able to introduce k for the first time offering a more exact value by means of the law of black body radiation . Before 1900, equations that included Boltzmann factors did not use any type ofenergy per molecule nor its constant but instead included a constant form of gas R and a series of macroscopic energies for the substance .

During the second half of the 19th century, there was disagreement over whether atoms and molecules were real and whether molecules that were measured by atomic weights were the same as physical molecules . In 2013, the UK National Physical Laboratory used microwave and acoustic resonance measurements to be able to calculate the speed of sound of a monatomic gas in a triaxial ellipsoid chamber and thus have a more accurate value for the constant, such as part of the revision of the International System of Units .


The value of the constant of Boltzmann is approximately 1.3807 x 10 -23 joules per kelvin (J · K -1 ). Generally value is measured using the determination of the accepted by the Boltzmann constant and is based on the value determination of the universal constant of the R gases by a technique that measures the speed of propagation having an acoustic wave in argon . Currently its value can also be measured by means of an application of laser absorption spectroscopy .

Importance of the Boltzmann constant

Boltzmann’s constant is important because it helps identify the temperature and energy kinetics relative to each molecule of gas . It also helps to clarify the relationship between an electric current and an electric potential , which results in a thermal voltage observed at the pn junction of the semiconductors . In addition, Boltzmann’s constant is one of the fundamental numbers that are used to be able to make a description about an essentially important relationship in molecular thermodynamics and statistical mechanics .

Because Boltzmann’s constant is expressed in terms of energy divided by temperature , it is compared to the expression for entropy . Boltzmann’s constant has been key to understanding how the microstates of a system are interrelated with its macro- states and the proportions in which change occurs. This essential number links the statistical mechanics of entropy with the classical understanding of thermodynamic entropy .

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