Refractive indices, defined table

Table G1.5.7 lists the physical and chemical properties (specific gravity, SG refractive index, r optical activity, a) of citrus oils defined by the Food Chemicals Codex (NRC, 1981).

In Tables IX to XI the values of the refractive index, w2, for a number of temperatures of treatment are also given. The specific refraction defined according to... 

Solvent polarity is very difficult to define, but essentially refers to the solvation power of a solvent. Quantitative determination of solvent polarity is equally difficult, and quantitative methods rely on physical properties such as dielectric constant, dipole moment, and refractive index. It is not possible to determine the solvent polarity by measuring an individual solvent property due to the complexity of solute-solvent interactions and for this reason empirical scales of solvent polarity, based on chemical properties, are most widely used. The principal properties used to estimate solvent polarity are summarized in Table 2 and the most important of these methods are embellished below. 

From Maxwell s theory of electromagnetic waves it follows that the relative permittivity of a material is equal to the square of its refractive index measured at the same frequency. Refractive index given by Table 1.2 is measured at the frequency of the D line of sodium. Thus it gives the proportion of (electronic) polarizability still effective at very high frequencies (optical frequencies) compared with polarizability at very low frequencies given by the dielectric constant. It can be seen from Table 1.2 that the dielectric constant is equal to the square of the refractive index for apolar molecules whereas for polar molecules the difference is mainly because of the permanent dipole. In the following discussion the Clausius-Mossoti equation will be used to define supplementary terms justifying the difference between the dielectric constant and the square of the refractive index (Eq. (29) The Debye model). 

The right hand side of Equation (51) traditionally defines the factor molar refraction [/ ], which is therefore the same as molar electronic polarisability. Since refractive index is dimensionless, [7 ] has the dimensions of volume and is a function of molar volume. It is also an additive and constitutive property, so that the molar refraction of a compound or a group can be calculated by summation of the refraction equivalents of its constituents. Tables of refraction equivalents are to be found in most text books of physical chemistry, for example... 

The fields are constructed from the solution of Eq. (30-32b) for hy and Eq. (30-33). This leads to the components in Table 12-10, where U, V and W are now defined in terms of n, nl, and The differences with the TM mode fields in Table 12-1 arise solely due to the changes in refractive-index values. This is evident from comparing Eqs. (30-32b) and (30-33) with Eq. (12-20) and (12-23), respectively. The eigenvalue equations in Table 12-11 follow by demanding continuity of and hy at the interfaces, and the remaining expressions follow from Table 11-1, with the exception of the group velocity, which is calculated from the modified form of Eq. (31-31). 

Brdk properties refer to properties measured while taking the whole crude into account. These properties are typically density, viscosity, refractive index, etc. and are useful but do not sufficiently define the crude or a cut from this crude. DistiUation-based properties refer to the bulk properties measured for small amounts of crude based on that small amount s boiling point Typically, we present these properties as a function of these small amounts as density distributions, boiling points distributions (TBP, D-86, D-2887), etc. When a refiner considers particular crude for use, the collection of bulk and distillation based properties form particular crude s assay. This assay indicates how much of a given cut (or product) we can produce from a given crude. Tables 2.5 to 2.8 show crude assays for Arab Heavy and Arab Light crude. 

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