Molar refractivity
Molar refractivity,[1] , is a measure of the total
index of refraction, and the pressure
.
The molar refractivity is defined as
where is the Avogadro constant and is the mean polarizability of a molecule.
Substituting the molar refractivity into the
Lorentz-Lorenz
formula gives, for gasses
where is the refractive index, is the pressure of the gas, is the
universal gas constant
, and is the (absolute) temperature. For a gas, , so the molar refractivity can be approximated by
In
SI
units, has units of J mol−1 K−1, has units K, has no units, and has units of Pa, so the units of are m3 mol−1.
In terms of
molecular weight
M, it can be shown that:
References
- ^ W. Foerst et.al. Chemie für Labor und Betrieb, 1967, 3, 32-34. https://organic-btc-ilmenau.jimdo.com/app/download/9062135220/molrefraktion.pdf?t=1616948905
- ISBN 0-521-64222-1