材料期刊网

The molal enthalpies of solution of VOSO(4)center dot 2.76H(2)O(s) with various molalities in water and in aqueous sulfuric acid (0.5 mol.kg(-1)) Delta(s)H(m), were measured by a solution-reaction isoperibol calorimeter at 298.15 K. The value of -Delta(s)H(m) in aqueous sulfuric acid was lower than that in water, which shows that energy state of VOSO(4) in aqueous H(2)SO(4) was higher than that in pure water. An improved Archer's method was put forward in terms of ionic association equilibrium of VOSO(4) and second dissociation equilibrium of H(2)SO(4). Using the improved method, the standard molal enthalpies of solution Delta(s)H(m)(circle minus) = 29.18 kJ.mol(-1) in pure water and Delta(s)H(m)(circle minus) = -25.79 kJ.mol(-1) in aqueous sulfuric acid were obtained, respectively. According to calculation, the molality of VO(2+) was larger in VOSO(4)-H(2)SO(4) mixed solution than that in water.