لخّصلي

Since n is dimensionless, the presence of the factor M shows that the molar refraction is a type of molar volume and is an additive property and also partly a constitutive property.For a study of the molar refractions of a large number of compounds, atomic refractions and different bond contributions are obtained.

Introduction

The refractive index of a substance is denoted by the symbol "n" and is defined as the ratio of the velocity of light in vacuum to that in the medium being investigated.

The index of refraction is a function of both wavelength and temperature and represented usually as where T is the temperature in degrees centigrade and D is the sodium D line usually a doublet at wavelength 5890-5896 A°.

For many liquids the variation of refraction index with temperature dn/dT-4 x 10-4. The theoretical work of Lorentz and Lorenz indicated that the molar refraction of a compound defined by the expression n²-1 M RM

²+1 d

Where M is the molecular weight and "d" the density was a characteristic property of a substance independent of the temperature.

Since n is dimensionless, the presence of the factor M shows that the molar refraction is a type of molar volume and is an additive property and also partly a constitutive property.

For a study of the molar refractions of a large number of compounds, atomic refractions and different bond contributions are obtained.