Thermodynamics of thallium alkanoates V. Heat capacity and thermodynamic functions of thallium(I) n-decanoate from 6 to 480 K

Abstract

The heat capacity of thallium(I) n-decanoate was measured by adiabatic calorimetry from 6 to 350 K and by d.s.c. from 200 through 480 K. Excellent overlap occurs over the common temperature range of both techniques. Four solid-to-solid transitions were found; at 232.9 K, at 288.3 K, and two more at 305.6 K (very sharp with a for the maximum of about 1700R), and at 327.6 K. The corresponding values of [Delta]trsHmo are 352R[middle dot]K, 83.8R[middle dot]K, and 1026R[middle dot]K (for the set of two transitions), respectively, and of [Delta]trsSmo are 1.461R, 0.283R, and 3.19R (for the set of two), respectively. The compound melts to a liquid-crystal phase at 450.0 K: [Delta]trsHmo = 682R[middle dot]K, [Delta]trsSmo = 1.68R. Finally, "clearing" occurs at 484.0 K: [Delta]trsHmo = 307R[middle dot]K, [Delta]trsSmo = 0.63 R. Smoothed thermophysical functions are tabulated through "clearing" at selected temperatures.