| Abstract
| - The novel linear concentration relations and the simple predictive equations for the thermodynamic properties(chemical potential, activities of all BJ (J = 1, 2, ..., j), Gibbs free energy, thermal properties, and volumetricproperties) have been proposed for the multicomponent system B1−B2−...−Bj−C1−C2−...−Ck−A1−A2−...−Ai in terms of the concentration and the properties of its subsystems BJ−C1−C2−...−Ck−A1−A2−...−Ai(J = 1, 2, ..., j) of equal activities of all C1, C2, ..., Ck and A1, A2, ..., Ai. It has been shown that the processof mixing the nonideal systems BJ−C1−C2−...−Ck−A1−A2−...−Ai (J = 1, 2, ..., j) of equal activities of allC1, C2, ..., Ck and A1, A2, ..., Ai shows ideal mixing behavior and that the newly established equations are thesame in form as those for mixing the ideal systems BJ−C1−C2−...−Ck−A1−A2−...Ai (J = 1, 2, ..., j) ofequal mole fractions of all C1, C2, ..., Ck and A1, A2, ..., Ai. The thermodynamic basis for the ideal mixingbehavior has been presented. It has been shown that, while Raoult's law can describe the ideal behavior ofmixtures based on similar components, the present equations describe a new type of “ideal” behavior ofnonideal mixtures B1−B2−...−Bj−C1−C2−...−Ck−A1−A2−...−Ai at constant activities of all C1, C2, ..., Ckand A1, A2, ..., Ai. The linear concentration relations have been tested by comparing with the isopiesticmeasurements for the saturated systems glucose−sorbitol−sucrose(sat)−water, glucose−mannitol−sucrose(sat)−water, sorbitol−glucose−mannitol(sat)−water, sorbitol−sucrose−mannitol(sat)−water, mannitol−sorbitol−sucrose(sat)−water, mannitol−sucrose−urea(sat)−water, and sucrose−urea−mannitol(sat)−water at 298.15 K.As expected, the former six systems conform to the new relations very well, but large deviation is observedin the last system.
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