HEAT-CAPACITY AND CHEMICAL-EQUILIBRIA OF LIQUID SELENIUM

In the reported experiments, heat capacities of liquid selenium have been measured by computer interfaced differential scanning calorimetry in the metastble region with an accuracy of plus or minus 1% from 330 to 520 degree K. To avoid crystallization, the measurements were done on cooling. A semiquantitative fitting of the heat capacity to vibrational energy contributions, free volume (hole) effects, and heats of reaction from the changes in the ring-chain and depolymerization equilibria was possible to within plus or minus 5% of the newly measured and literature data between the glass transition temperature (ca. 303 degree K) and 1000 degree K. It could be established that the shift in the ring-chain equilibrium is not the major reason for the overall decrease in heat capacity above the glass transition temperature. The floor temperature, which was earlier placed at about 356 degree K, is possibly below the glass transition temperature. The increase in heat capacity beyond 800 degree K has been linked with the depolymerization reaction.