Partial Molar Enthalpy

mole fraction of A

0.5

non-ideal parameter

50

The enthalpy of a binary mixture of

A

and

B

is plotted as a function of the mole fraction of component

A

. For an ideal solution, the enthalpy of the mixture is a linear function of the molar enthalpies of the pure components. For a non-ideal solution, you can vary a parameter that describes the deviation from ideality. One can define partial molar enthalpies, which are obtained by drawing a tangent at the value of the mole fraction of the solution. The intersections of this tangent with the

y

axis at

x

A

=0

and

x

A

=1

correspond to the partial molar enthalpies of

B

and

A

, respectively. You can also vary the mole fraction of

A

in the mixture, as indicated by the dot on the curve.