Investigation into heat capacity of aqueous solutions of perchlorates of the periodic system group 2 elements

Specific thermal capacity of magnesium, calcium, strontium, barium, cadmium and mercury perchlorates aqueous solutions were measured at 25 deg C and concentration interval from 0.1 to 4 mol. The apparent molal thermal capacity of the investigated perchlorates Fsub(csub(p)) and the thermal capacity change ΔCsub(p) during dissolving anhydrous perchlorates in water were calculated. Specific features of interaction of cations of some Periodic System sections with water formed a basis for the discussion of the results. The conclusion is drawn that in the alkaline earth metal perchlorate solutions the sequence of ΔCsub(p) values in the subgroups is determined by the competition of two factors mainly: destructurization by water ions and intensity of their interaction with coordinated water. In the zinc subgroup the polarization factor for coordinated water and the effect of extraspheric water molecules association, are more important