Enthalpy of Mixing and Deviation from Raoult's Law: Interactive Simulation

This simulation runs in your browser. Try to predict the behavior when a parameter changes before using a slider to change that parameter.   A screencast below explains how to use this simulation.

Simulation: Partial Molar Enthalpy

The molar enthalpy of a binary mixture of A and B is plotted as a function of the mole fraction of component A. The end points of the molar enthalpy are the pure-component enthalpies (HA and HB). The partial molar enthalpies \(\overline{H}_A\) and \(\overline{H}_B\), are obtained by drawing a tangent line at the black point (indicating the mole fraction of the solution). The intersections of this tangent with the y axis at xA = 0 and xA = 1 correspond to \(\overline{H}_B\) and \(\overline{H}_A\), respectively. You can change the mole fraction of A in the mixture with the slider. For an ideal solution (non-ideal parameter = 0), 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 represents the deviation from ideality.

Try to answer this question before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
If mixing is exothermic, is the partial molar enthalpy of component A greater than or less than the pure-component enthalpy?