Standard enthalpies of zinc and copper methanesulfonate tetrahydrates formation

Enthalpies of dissolution of zinc Zn(SO3CH3)2.4H2O and copper Cu(SO3CH3)2.4H2O methanesulfonate tetrahydrates in water were measured at 298.15 K by isoperibol solution calorimeter. Obtained values were recalculated to infinite dilution by Debay-Hukkel equations. There is a slight exothermic effect when the zinc salt dissolves (Delta solH0m =-0.24 +/- 0.18 kJ/mol), while the copper salt is dissolved endothermically (Delta solH0m = 14.95 +/- 0.39 kJ/mol). Standard enthalpies of salts formation at 298.15 K were calculated on the basis of the experimental and literature data of ions formation in aqueous solutions by Hess Law. Corresponding values of standard enthalpies of formation are equal Delta fH0298.15 =-2667 +/- 9 kJ/mol and Delta fH0298.15 =-2464 +/- 9 kJ/mol for Zn (SO3CH3)2.4H2O and Cu(SO3CH3)2.4H2O, respectively.