Convert Calories per Kelvin to Kilojoules per Kelvin

The Calorie per Kelvin (symbol: cal/K) is a unit of entropy. A CGS entropy unit equal to exactly 4.184 J/K (using the thermochemical calorie definition per NIST SP 811). cal/K is a legacy unit that persists in older chemistry and biochemistry literature, with the equivalent molar form cal/(K·mol) (often abbreviated 'e.u.' for 'entropy unit' in older textbooks) appearing routinely in: classical physical-chemistry references pre-1980 (Lewis-Randall, Pitzer-Brewer thermodynamics texts), biochemistry literature on protein-folding entropy (typical ΔS_folding ranges from -50 to +50 cal/(K·mol) per residue), enzymology free-energy diagrams (Eyring-transition-state analysis), and pharmaceutical drug-binding thermodynamics (isothermal titration calorimetry / ITC papers in J. Mol. Biol., Biochemistry, Protein Sci. through the 1990s). The bond-dissociation entropy of H₂(g) → 2H(g) at 298 K is ΔS° = +24.4 cal/(K·mol). Modern publications increasingly use SI J/K, but cal/K appears in cross-references to older databases (NIST WebBook still dual-lists), in NMR-relaxation thermodynamic-cycle interpretation, and in physical-organic-chemistry literature where Arrhenius pre-exponential factors are quoted with entropy in cal-units.

It belongs to the metric measurement system.

Calories per Kelvin are commonly used in thermodynamics, refrigeration cycles, and chemical engineering.

The Kilojoule per Kelvin (symbol: kJ/K) is a unit of entropy. A metric entropy unit equal to exactly 1,000 J/K. kJ/K is the practical working unit for industrial/plant-scale thermodynamic analysis where total entropy flows are large enough that J/K becomes unwieldy: steam-power-plant Rankine-cycle second-law (exergy) evaluations per ASME PTC 4 / VDI 4655 / IEC 60953 standards, large refrigeration-cycle COP optimization (Carnot-to-actual entropy generation comparisons for chillers > 1 MW cooling capacity), industrial combustion entropy balances (cement-kiln Cl-Pre-Calciner systems, glass-furnace regenerators, blast-furnace iron-reduction processes), and gas-turbine combined-cycle (CCGT) plant heat-balance diagrams per IEC 60534. A typical 600 MW supercritical coal-fired power station rejects entropy at ~3,000 kJ/(K·s) to its cooling tower; nuclear PWR steam-generator secondary-side entropy generation ~5,000 kJ/(K·s); industrial-scale ammonia-synthesis (Haber-Bosch) reactor entropy generation ~50 kJ/(K·s). The kJ/K unit is dominant in EBSILON Professional, Aspen Plus, GateCycle, and Thermoflex cycle-simulation software output reports.

It belongs to the metric measurement system.

Kilojoules per Kelvin are commonly used in thermodynamics, refrigeration cycles, and chemical engineering.