Properties of mixtures via parametric analogy

Determining physical-property data is critical in designing chemical processes. For binary mixtures, it is often difficult to find values of physical properties over the range of temperatures and concentrations that will occur throughout a process. This is so even for mixtures of some fairly common compounds. 

Quick estimates of properties are needed during the early stages of design. This can often be done, and with reasonable accuracy, by employing what is known as the method of the parametric analogy. This method is based on ideas presented earlier by one of the authors [i]. 

Assume that we are dealing with a two-component, mutually soluble system. Also assume that we have a curve of a property vs. concentration at one temperature. The curve can be plotted from published data. 

assume that, for both compounds, there is no deviant behawor owing to changes in either temperature or concentration. 

for other temperatures, the shape of the curve will remain essentially constant. The only difference will be in its relative position as temperature varies. 

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