Binary mixtures

Abstract

Abstract Binary mixtures will here be considered as a mixture of a fluid substance, such as those described in Chapter 1, which will be always called component 1, and a second substance, component 2. The binary mixtures that are important in supercritical fluids broadly fall into two areas, d pending on the molar mass and critical temperature of component 2. In the first general area the second component has a molar mass and critical temperature mostly above, but not far above, those of component 1. In these cases the second component is added often in sizeable amounts to modify the solvation character of the fluid or, for example, to provide a reagent. Cases where the molar mass or the critical temperature of component 2 is lower than that of component 1 include the addition of a gas, such as hydrogen, to act as a reagent. The second area where consideration of binary mixtures is important is when involatile solutes of higher molar mass are dissolved in the fluid in the process of carrying out extraction, separation, or chemical reaction. The molar masses and critical temperatures of these second components will be typically much higher than that of component I. In summary there are two areas of binary mixtures: in the first the component 2 is a modifier of relatively low molar mass; and in the second component 2 is a heavy solute.