Models for the standard partial molar volume

In this section we will briefly summarize the models proposed to assess the standard partial molar volume of solute at high temperature and pressure. 

The standard state partial molar volume or partial molar at infinite dilution of electrolytes, 2 , reflects the solute- 

By using this extra-thermodynamic assumption we get h+ = -6.7 + 0.7 cm moT at 25 °C. Other reference electrolytes could be chosen, but the partial molar volume of the ion results close to the above-cited values. 

In order to avoid these non-thermodynamic assumptions in the assigning of ionic partial molar volume at infinite dilution, it is useful to define a conventional V ° for ions based on the value Vfl = 0 at all temperatures and pressures. 

The absolute value of the partial molar volumes at infinite dilution of an ion of charge z, at 25 °C can be calculated from the conventional one by means of. 

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