Boltzmann's constant, also called the Boltzmann constant and symbolized k or k B , defines the relation between absolute temperature and the kinetic energy contained in each molecule of an ideal gas . This constant derives its name from the Austrian physicist Ludwig Boltzmann (1844-1906), and is equal to the ratio of the gas constant to the Avogadro constant .
The value of Boltzmann's constant is approximately 1.3807 x 10 -23 joule s per kelvin (J · K -1 ). In general, the energy in a gas molecule is directly proportional to the absolute temperature. As the temperature increases, the kinetic energy per molecule increases. As a gas is heated, its molecules move more rapidly. This produces increased pressure if the gas is confined in a space of constant volume, or increased volume if the pressure remains constant.
Also see Table of Physical Constants .