Ebullioscopic Constant
The boiling point elevation produced by a one-molal solution of a non-electrolyte in a given solvent.
Formula / equation
K_b = RT_b²M / ΔH_vap
Unit
K·kg/mol
In depth
The constant is a property of the solvent alone, determined by its boiling point, molar mass and enthalpy of vaporisation. Solvents with large K_b give bigger, more easily measured elevations, which is why camphor and benzene were favoured for molar mass determinations.
Examples in the real world
Water has K_b = 0.512 K·kg/mol, benzene 2.53, and camphor a very large 5.95.