kJmolK

kJmolK is a unit used in thermodynamics and physical chemistry to express quantities that are both molar (per mole) and temperature-dependent. It stands for kilojoules per mole per kelvin, and is commonly written as kJ/(mol·K) or, in shorthand, kJ mol-1 K-1. In SI terms, it is equivalent to 1000 J/(mol·K). The index indicates that the quantity is per amount of substance (per mole) and per unit of temperature (per kelvin).

This unit is most often encountered with molar heat capacities, such as Cp,m and Cv,m, which describe how much energy is needed to raise the temperature of one mole of a substance by one kelvin. It also appears in data for molar entropies and other thermodynamic properties that vary with temperature. Examples of typical values include Cp,m for water about 0.075 kJ/(mol·K) and Cp,m for air around 0.029 kJ/(mol·K), though exact figures depend on temperature and phase.

When converting to the base SI unit, multiply by 1000 to convert from kJ/(mol·K) to J/(mol·K). The unit is related to, but distinct from, J/(mol·K) in notation; many data tables present values in either form depending on conventions. Ambiguity can arise from informal notations like kJ/mol/K; the preferred form is kJ/(mol·K) to clearly distinguish per mole and per kelvin.

See also: molar thermodynamic quantities, such as Cp,m and S_m(T), and standard references for thermophysical data.