Margules function

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A Margules function is a function added to the Raoult's law description of a liquid solution to account for deviations from ideality. See also Margules activity model.

The amended Raoult's law description of the vapor pressure above the solution becomes:

P1=P*1x1fM,1
P2=P*2x2fM,2

The Margules function has the general form:

fM,1 = exp(αx22+βx23+γx23+δx24+...)

The function always contains the opposite mole fraction x2 (= 1-x1 for a binary system). The numbers of Margules parameters α, β, γ, δ, .. varies. The larger the deviations from ideality the more parameters are required.

The Gibbs-Duhem relation can be used to fix the Margules function for the second component once the first has been chosen.

The case where only one parameter α is needed is known as the regular solution model.

See also[edit]

Van Laar equation

External links[edit]