The standard enthalpy of formation ( Δ \-f H\+\+ \-\-m[K\-2Zn(IO\-3)\-4·2H\-2O,s,298.2K]=-2210.68 kJ·mol\+\{-1\}) of a double salt K\-2Zn(IO\-3)\-4·2H\-2O is determined by solution calorimetry in a isoperibel reaction calorimeter. The calorimetric solvent is an acid solution consisting of 3 mol·L\+\{-1\} HNO\-3. Accoding to the HESS Law, we designed a rational thermochemical cycle. Simultaneously, the Δ \-f H\+\+ \-\-\{m 298.2K\} was calculated from the data of the DSC curve. The values obtained by the two methods were compared.
The standard molar formation enthalpies of （A＋）2Cd2（SO4）3[A＋is NH-4＋or K＋ ] are determined from the enthalpies of dissolution （ΔSHm） of [（A＋）2SO4（s）＋ 2CdSO4（s）] and （A＋ ）2Cd2（SO4）3（s） in twice distilled water or 3 mol· L－ 1 HNO3 solvent respectively,at 298.2 K,as: Δ fHm[（NH4）2Cd2（SO4）3,s,298.2K]=－ 3031.74± 0.08 kJ· mol－1 Δ fHm[K2Cd2（SO4）3,s,298.2K]=－ 3305.52± 0.17 kJ·
