Portal de Periódicos da CAPES

The unsymmetrical reciprocal molten-salt mixture (Na+ + Rb+ + F− + SO42−) calorimetric measurement and evaluation of the excess molar enthalpies

1984; Elsevier BV; Volume: 16; Issue: 9 Linguagem: Inglês

10.1016/0021-9614(84)90038-7

1096-3626

G. Hatem, Marcelle Gaune‐Escard,

Thermal and Kinetic Analysis

The excess molar enthalpies HmE of the two molten-salt mixtures {(1−x)Rb2SO4 + xNaF} and {(1−x)Na2SO4 + xRbF} have been measured by direct high-temperature calorimetry. These constitute the diagonals of the (Na+ + Rb+ + F− + SO42−) unsymmetrical ternary reciprocal system. The experimental uncertainty has been evaluated from statistical calculations. From the measured HmE's we obtained the molar enthalpy difference ΔHm,0 associated with the exchange reaction characterizing this reciprocal mixture: 0.33Na2SO4(l)+0.67RbF(l)=0.33Rb2SO4(l)+0.67NaF(l) The value was found to be in good agreement with that calculated from the standard thermodynamic quantities relative to the four pure salts. An estimation procedure enabled us to calculate the ternary excess molar enthalpies for the two diagonals which we then compared with those obtained experimentally.