Thermodynamics of Selected Aqueous Rare-Earth Elements Containing Triflate Salts at T=(288.15, 298.15, 313.15 and 328.15) K and p=0.1 MPa

Abstract

Aqueous acidified solutions of the rare-earth-element (REE) triflates (Gd(CF3SO3)3(aq), Dy(CF3SO3)3(aq), Nd(CF3SO3)3(aq), Er(CF3SO3)3(aq), Yb(CF3SO3)3(aq) and Y(CF3SO3)3(aq)) have been prepared by the dissolution of the corresponding REE oxides in dilute aqueous trifluoromethanesulfonic acid (triflic acid, CF3SO3H(aq)). Relative densities and relative massic heat capacities have been measured for these systems over the approximate ionic strength range 0.10≤I/(mol⋅kg−1)≤1.35 at T=(288.15, 298.15, 313.15 and 328.15) K and p=0.1 MPa. These measurements were completed using a Sodev O2D vibrating tube densimeter and Picker-flow microcalorimeter, respectively. Relative densities and relative massic heat capacities for aqueous solutions of triflic acid and its sodium salt have also been measured over the concentration range 0.018≤m2/(mol⋅kg−1)≤0.23 over the same temperature range at p=0.1 MPa.