VE - Excess Volumes, Mixture Densities
The data bank DDB-VE contains a large amount of mixture densities and excess volumes. Excess volumes represent the deviation from ideal mixing volume and are crucial for describing the effect of pressure on the real behavior (activity coefficients and fugacity coefficients). The figure on the right shows the excess volume for the well known system ethanol-water as function of liquid mole fraction for several different temperatures. As the excess volume is negative, one can expect to yield a smaller volume of the mixture than the sum of the pure component volumes when mixing pure ethanol and water. At room temperature mixing of 1 dm3 each of water and ethanol will lead to only 1.92 dm3 of mixture. In case of immiscible liquids, the size of the immiscible region can be influenced by pressure as the system would shift to the state of lower volume upon pressure increase. In case of negative excess volumes, applying sufficient pressure often leads to complete miscibility. This can be a great advantage e.g. in case of chemical reactions, where the reaction rate is limited by the transport through the phase boundary. VE contains 47,972 mixture density and excess volume data sets (558,377 data points) from 5,085 references for 2,057 components and 12,347 different systems (10,683 binary, 1,605 ternary 51 quaternary and 8 quinary systems)(Version 2011). Selected Scientific Papers (Experimental Data)
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