Volume Fraction

\phi_i \equiv rac{N_iv_i}{V}

where the total volume of the System is the sum of the contributions from all the chemical species

:

V = \sum_j  N_jv_j \,

The volume fraction can also be expressed in terms of the numbers of Moles by transferring Avogadro's Number

N_A

≈ 6.023 x 10²³ between the factors in the numerator.

:

\phi_i \equiv rac{n_iV_i}{V}

where

n_i = N_i / N_A

is the number of moles of

i

and

V_i

is the molar volume, and

:

V = \sum_j  n_jV_j \,

As with mole fractions, the dimensionless volume fractions sum to one by virtue of their definition.

:

\sum_i  \phi_i \equiv 1 \,

Thermodynamic Functions using volume fractions reduce to mole-fraction expressions for mixtures of rigid molecules of roughly equal size. For Macromolecule s, there is a question about whether they behave as flexible, Random Coil s (see Flory-Huggins Solution Theory ), or whether they have compact Structures like Globular Protein s. In addition to Entropic questions, there are others concerning Energy .

For real mixtures, see Partial Molar Volume .

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	CATEGORIES ABOUT VOLUME FRACTION

	physical chemistry

	thermodynamics

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