THE INTEGRAL HEATS OF SOLUTION OF RARE-EARTH ISOTHIOCYANATE HYDRATES IN AQUEOUS AMINO-ACID SOLUTIONS

The integral heats of solution of nine kinds of RE(NCS)3 . nH2O (n = 6 for RE = Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Y) in aqueous glycine soluti on, of nine kinds of RE(NCS)3 - nH2O (n = 7 for RE = La, Pr, Nd; n = 6 for RE = Gd, Dy, Ho, Tm, Yb, Y) in aqueous alanine solution and of te n kinds of RE(NCS)3.nH2O (n = 7 for RE = La, Pr, Nd; n = 6 for RE = Sm , Eu, Gd, Dy, Ho, Yb, Y) in aqueous serine solution have been measured calorimetrically at 298.15 +/- 0.1 K. In the above measurements, the molar ratio of RE(NCS)3.nH2O(c):amino acid(c):H2O(1) is 1:3:600. The i ntegral heats of Dy(NCS)3.6H2O in more dilute aqueous solutions of gly cine, alanine and serine were also measured separately. At this time, the molar ratio of Dy(NCS)3.6H2O(C): amino acid (c):H2O(l) was changed to 1:3:1200 and 1:3:2400. Some valuable results have been obtained an d are analysed with discussion.