Since the average molar masses of the ILs and DSILs (Mw) increase proportionally with increasing xdic, a close linear relationship also exists between the average molar masses of systems A, AB0.1-AB0.9 and B and their measured density. This is confirmed by the fact that all analyzed systems are characterized by very similar molar volumes (Vm 20 ), defined as the quotient of the molar mass of a substance and its density at a given temperature. The average value of this parameter for all ILs and DSILs is approx. 531.4 cm 3 mol -1 , and the calculated extreme values (530.7 cm 3 mol -1 for AB0.9 and 532.0 cm 3 mol -1 for AB0.1) differ from the average value by approximately 0.1 %. The negligible differences between the Vm 20 values also indicate that other parameters proportional to this physical quantity also have similar values.