Distillation Principle Of Chemical Reagents

The main purpose of distillation is to separate volatile and semi-volatile impurities from chemical reagents containing impurities or to evaporate volatile and semi-volatile substances, leaving non-volatile and hard-to-volatile impurities. The change in saturated vapor pressure of a substance at different temperatures is the basis of distillation separation. In general, if the vapor pressures of the two components in the liquid mixture are significantly different, more volatile and semi-volatile components in the vapor phase can be enriched. The two phases-the liquid phase and the vapor phase-can be recovered separately, and the volatile and semi-volatile components are concentrated in the gas phase and the non-volatile components are concentrated in the liquid phase.

In addition to hydrocarbon mixtures and a few other examples, Raoult's law and Dalton's law can be applied to ideal mixture systems, and mixture solutions often do not follow the ideal vapor phase-liquid phase behavior. By applying these two laws, the specific volatility (aAB) of the two components of a binary system can be obtained: aAB = (YA/YB)/ (XA/XB) = P0A/ P0B where YA and YB are respectively in equilibrium The mole fractions of components A and B in the gas phase, XA and XB are the mole fractions of components A and B in the liquid phase at equilibrium, and P0A and P0B are the vapor pressures of components A and B at equilibrium, all obey Raouilt's law . As aAB increases, the degree of enrichment also increases.