Excess molar quantity

Excess molar quantities are properties of mixtures which characterize the nonideal behaviour of real mixtures. They are the difference between the partial molar property of a component in a mixture and that of the pure component. The most frequently used excess molar quantities are the excess molar volume, excess molar enthalpies and heat capacities, excess chemical potential.

Contents

Definition

By definition, excess properties of a mixture are related to those of the pure substance by:

z^E=z-\sum_i x_iz^*_i.

Here * denotes the pure substance, E the excess molar property, and z corresponds to the specific property under consideration. From the definition of partial molar properties,

z=\sum_i x_i \bar{Z_i},

substitution yields:

z^E=\sum_i x_i(\bar{Z_i}-z_i^*).

See also

References

Frenkel, Daan; Smit, Berend. Understanding Molecular Simulation : from algorithms to applications. San Diego, California: Academic Press. ISBN 0-12-267351-4. 

External links

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