Cryoscopic constant

from Wikipedia, the free encyclopedia
Absolute Beckmann thermometer

The cryoscopic constant (from cryoscopy , see below) is a measured variable from physical chemistry . It indicates the temperature (in Kelvin ) by which the melting point of a solution is reduced compared to that of the pure solvent (melting point or freezing point lowering ) when 1  mol of a non- volatile substance is dissolved in 1 kg of the pure solvent.

The cryoscopic constant can be calculated using the following formula:

Some values

solvent Freezing point in ° C Cryoscopic constant
in K kg / mol
water 0 −1.853
naphthalene 80.2 −6.80
chloroform −63.5 −4.68
benzene 5.5 −5.12
Camphor 179 −39.7
Ethanol −114.6 −1.99
Cyclohexane 6.4 −20.2
Carbon tetrachloride −23 −30


The cryoscopic constant can be used to determine the molar mass of a soluble substance from the depression of the freezing point by cryoscopy (for example according to Beckmann using a Beckmann thermometer ).

See also

Individual evidence

  1. ^ Gordon Aylward, Tristan Findlay: SI Chemical Data , Sweden, John Wiley & Sons, 2002, 5th edition, ISBN 0-470-80044-5 .
  2. Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 4: M-Pk. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1985, ISBN 3-440-04514-5 , pp. 2650-2651.