Apparent molar volumes and apparent molar heat capacities of Pr(NO3)3(aq), Gd(NO3)3(aq), Ho(NO3)3(aq), and Y(NO3)3(aq) at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa

Abstract

Apparent molar volumes and apparent molar heat capacities of Pr(NO 3 ) 3 (aq), Gd(NO 3 ) 3 (aq), Ho(NO 3 ) 3 (aq), and Y(NO 3 ) 3 (aq) at T = (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa AbstractRelative densities and relative massic heat capacities have been measured for acidified solutions of Y(NO 3 ) 3 (aq), Pr(NO 3 ) 3 (aq), and Gd(NO 3 ) 3 (aq) at T = (288. 15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa. In addition, relative densities and massic heat capacities have been measured at the same temperatures and pressure for Y(NO 3 ) 3 (aq) and Ho(NO 3 ) 3 (aq) solutions without excess acid (n.b. measurements at T = 328.15 K for Ho(NO 3 ) 3 (aq) were not performed due to the limited volume of solution available). Apparent molar volumes and apparent molar heat capacities for the aqueous salt solutions have been calculated from the experimental apparent molar properties of the acidified solutions using YoungÕs rule, whereas the apparent molar properties of the solutions without excess acid were calculated directly from the measured densities and massic heat capacities. The two sets of data for the Y(NO 3 ) 3 (aq) systems provide a check of the internal consistency of the YoungÕs rule approach we have utilised.The concentration dependences of the apparent molar volumes and heat capacities of the aqueous salt solutions have been modelled at each investigated temperature using the Pitzer ion interaction equations to yield apparent molar properties at infinite dilution.Complex formation within the aqueous rare earth nitrate systems is discussed qualitatively by probing the concentration dependence of apparent molar volumes and heat capacities. In spite of the complex formation in the aqueous rare earth nitrate systems, there is a high degree of self-consistency between the apparent molar volumes and heat capacities at infinite dilution reported in this manuscript and those previously reported for aqueous rare earth perchlorates.

Thermodynamic Properties of Ternary Solutions in the Water–Nitric Acid–Rare Earth Nitrate (Pr, Nd, Sm) Systems at 298.15 K

“…Again taking into account again 2% accuracy of samples compositions determination obtained results can be regarded as reliable. Measured by Hakin et al densities of diluted solutions in the H 2 O–HNO 3 –Pr­(NO 3 ) 3 system are also in excellent agreement with the Young rule (root mean square deviation, 0.01%).…”

Liquid–Liquid Equilibria in the Water–Nitric Acid–Europium Nitrate–Gadolinium Nitrate–Tributyl Phosphate System at 298.15 K

“…Therefore, we can compare our experimental data for the compositions I-0, II-0, and III-0, where nitric acid was added to prevent hydrolysis of REE nitrates with literature data in the binary H 2 O–Ln­(NO 3 ) 3 (Ln = Eu, Gd) subsystems. − The obtained deviations are less than the uncertainties of the composition and density in the present study. Besides the binary subsystems, densities in the H 2 O–HNO 3 –Gd­(NO 3 ) 3 system were also previously investigated by Hakin et al, but the concentration range of the solutions in the study of Hakin et al and the present work were different.…”

“…33−35 The obtained deviations are less than the uncertainties of the composition and density in the present study. Besides the binary subsystems, densities in the H 2 O−HNO 3 −Gd(NO 3 ) 3 system were also previously investigated by Hakin et al, 36 The results of determination of nitric acid by potentiometric acid−base titration of all investigated solutions, REE nitrates by ICP-AES method in the equilibrium phases, and the information about the total compositions in the H 2 O−HNO 3 − Eu(NO 3 ) 3 −Gd(NO 3 ) 3 −TBP system are given in Table 4.…”

Densities of the Ternary Systems Y(NO3)3+ La(NO3)3+ H2O, La(NO3)3+ Ce(NO3)3+ H2O, and La(NO3)3+ Nd(NO3)3+ H2O and Their Binary Subsystems at Different Temperatures

“…The fitted parameters were extrapolated to calculate the densities for the binary solution Y(NO 3 ) 3 + H 2 O in the molality range (0.23521 ≤ m M i X i o ≤ 0.41718) mol·kg −1 . The calculated densities were then compared with the densities measured by Hakin et al, and the agreement is good, with δ ρ = 1.8·10 −4 .…”