Definitions and conversion of concentrations

In the technique of distillation it is usual to calculate with mole fractions and mole percentages, as this greatly facilitates the computation of vapour volumes, vapour velocities, limiting velocities and so on. Since as a rule it is further the practice to consider the separability of components in sequence, the calculation may be baaed on that of binary mixtures, in which case of course, the second component may represent a mixture of several constituents. The average molecular weight is then determined by the formida  

Example Determination of the average molecular weight of a mixture  

If it is not otherwise stated, concentrations refer to the low-boiling component. The concentration can be reported as a fraction or percentage by volume or weight or as a molecular fraction or percentage. The fractional concentration is the ratio of the component to the sum of all components. 

To convert these numbers into percentages multiply by 100. 

Example Determination of the molecular fractions and percentages in a mixture  

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