The enthalpies of solution in water of M(NTO)(n) . m(2)H(2)O (M = meta
l, NTO = 3-nitro-1,2,4-triazol-5-one; M = Na, n = m = 1; M = La, Ce, P
r, Eu, Sm, n = 3, m = 7; M = Y, Yb, it = 3, in = 6; M = Dy, Tb, n = 3,
m = 5; M = Nd, n = 3; m = 8; M = Co, Mn, Mg, n = 2, m = 8) have been
measured calorimetrically at 298.15 K. By means of a thermochemical ca
lculation, the standard enthalpies of formation for the above fourteen
metal salt hydrates of NTO were obtained. With the help of the above-
mentioned data, literature data and Kapustinskii's equation. the latti
ce energies, lattice enthalpies and standard enthalpies of formation f
or twenty M(NTO)(n), and the lattice energies, lattice enthalpies and
standard enthalpies of dehydration were estimated for twenty M(NTO)(n)
.mH2O.