What is the mixture model used to determine the thermodynamic properties?
The model varies with each property. In most fixed properties is performed simply an average weighted by the molar volume. Some properties, as the properties of toxicity, however, are kept separate calculations for each fraction of the mixture and the probability of death from toxic dose is then considered by the boolean sum of each substance weighted contributions. The temperature dependent equations are adjusted according to the best fit equation that represents the proportional weighting of values to each fraction. For this reason, some mixtures may not be possible since it is not possible any appropriate adjustment curve. The system alerts with an error message if this problem occurs. Typically this represents situations where the mixture would not be in fact possible in the real world, indicating an error in the choice of substances.