Gaskonstant

Gaskonstant, in English commonly called the gas constant and denoted by R, is a fundamental physical constant used in thermodynamics and physical chemistry. It appears prominently in the ideal gas law, PV = nRT, where P is pressure, V is volume, n is the amount of substance in moles, and T is absolute temperature. The constant serves to relate macroscopic properties of gases to their microscopic behavior and is the basis for many derived equations in kinetics, thermodynamics, and statistical mechanics.

The molar gas constant has a value of approximately 8.314462618 J/(mol·K) in SI units. In other unit systems, R takes different numerical forms, such as 0.082057366 L·atm/(mol·K) or 8.314462618 kPa·L/(mol·K). The constant is related to Boltzmann's constant kB by R = NA · kB, where NA is Avogadro's number. This relationship links microscopic particle behavior to macroscopic gas properties.

Gaskonstant is a universal parameter, not a property of a specific substance, and its numerical value depends on the chosen units. It features in a wide range of equations beyond the ideal gas law, including those describing energy, entropy, and phase changes. The concept has historical roots in the work of 19th-century scientists such as Clausius and van der Waals, who helped formalize the law of ideal gases.