Boltzmann constant

The Boltzmann constant k (also k_B) is the ratio of the molar gas constant R to Avogadro's constant N_A. It can be thought of as the gas constant for a single molecule (or even for an arbitrary particle in a colloidal solution) rather than for a mole.

The Boltzmann Constant is illustrated here in the equation for the translational kinetic energy of a simple particle in thermal equilibrium with its surroundings:

$KE_{\mathrm {avg} }=\left({\frac {3}{2}}\right)kT$

Where KE_avg is the average kinetic energy of the particle, k is the Boltzmann Constant, and T is the temperature in kelvin.

For more info on this see the equipartition theorem

According to NIST the Boltzmann Constant has a value of 1.3806504 x 10^-23 J/K with a standard uncertainty of 0.0000024 x 10^-23 J/K and a relative uncertainty of 1.7 x 10^-6 (this is represented by the concise form 1.380 6504(24) x 10^-23 J/K

The Boltzmann Constant can also be represented in alternative units as 8.617385 x 10^-5 eV/K