Английская Википедия:Ebullioscopic constant

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Шаблон:Short description Шаблон:Use American English Шаблон:More citations needed In thermodynamics, the ebullioscopic constant Шаблон:Math relates molality Шаблон:Mvar to boiling point elevation.[1] It is the ratio of the latter to the former:

<math>\Delta T = iK_\text{b} b</math>

A formula to compute the ebullioscopic constant is:[2]

<math>K_\text{b} = \frac{RT_\text{b}^2 M}{\Delta H_\text{vap}}</math>

Through the procedure called ebullioscopy, a known constant can be used to calculate an unknown molar mass. The term ebullioscopy comes from the Latin language and means "boiling measurement". This is related to cryoscopy, which determines the same value from the cryoscopic constant (of freezing point depression).

This property of elevation of boiling point is a colligative property. It means that the property, in this case Шаблон:Math, depends on the number of particles dissolved into the solvent and not the nature of those particles.

Values for some solvents

Solvent[3] Шаблон:Math (in K⋅kg/mol)
Acetic acid 3.08
Benzene 2.53
Camphor 5.95
Carbon disulfide 2.34
Carbon tetrachloride 5.03
Chloroform 3.63
Cyclohexane 2.79
Diethyl ether 2.02
Ethanol 1.07
Water 0.512

See also

References

Шаблон:Reflist

External links


Шаблон:Thermodynamics-stub

  1. Шаблон:Cite web
  2. Шаблон:Cite web
  3. P. W. Atkins, Physical Chemistry, 4th Ed., p. C17 (Table 7.2)