| Popis: |
Solution and drop-calorimetric studies of magnesium uranate are described. From the solution experiments, the standard enthalpy of formation, ΔHfo(MgUO4, c, 298.15 K) was found to be −(1857.0 ± 1.3) kJ mol−1. The drop-calorimetric experiments gave values for the enthalpy increment {Ho(T) − Ho(298.15 K)} and heat capacity Cpo(T), which, over the temperature range 298.15 to 1400 K, are best represented by the equations: {H°(T) − H°(298.15K}J mol−1 = 110.268(TK + 3.3398 × 10−2(TK)2 −7.8127×10−6(TK3 − 35638; C°p(T)J K−1mol−1 = 110.268 + 6.6796 x 10−2(TK) −2.3438 × 10−6(TK)2 The complete thermodynamic functions of MgUO4 are tabulated from 298.15 to 1400 K. The spontaneity of the decomposition of BeUO4 to its component oxides is advanced as an explanation for the non-existence of this compound. |
