A thermodynamic investigation of some alkali-metal polyhalide compounds

An isoperibol solution reaction calorimeter has been constructed. The precision and accuracy of the calorimeter were checked by measuring the enthalpy of reaction of tris(hydroxymethyl)aminomethane, THAM, in:(a) excess 0.1 mol dm - aqueous hydrochloric acid(b) excess 0.05 mol dm -3 aqueous sodium hydroxide. The mean of 8 runs were: (a) DeltaH298 (1296 2-,C103-,Br03- and I0 3 have been calculated to investigate the relationshipbetween the 'thermochemical radius' and the geometric size of an ion of given symmetry. Lattice energies of alkali-metal and alkaline-earth salts containing these ions have been estimated and compared with literature values