Heat Capacity and Thermodynamic Properties of Cesium Pentaborate Tetrahydrate

摘要

This paper reports the molar heat capacities of β-CsB5O8·4H2O, which were measured by an accurate adiabatic calorimeter from 298 to 373?K with a heating rate of 0.1?K/min under nitrogen atmosphere. Neither phase transition nor thermal anomalies were observed. The molar heat capacity against temperature was fitted to a polynomial equation of Cp,m (J·mol?1·K?1)?=?618.07702?+?39.52669[T???(Tmax?+?Tmin)/2]/(Tmax???Tmin)/2]???3.46888[(T???(Tmax?+?Tmin)/2)/(Tmax???Tmin)/2]2?+?7.9441[(T???(Tmax+?Tmin)/2)/(Tmax???Tmin)/2]3. The relevant thermodynamic functions of enthalpy (HT???H298.15), entropy (ST???S298.15), and Gibbs free energy (GT???G298.15) of cesium pentaborate tetrahydrate from 298 to 375?K of 5?K intervals are also obtained on the basis of relational expression equations between thermodynamic functions and the molar heat capacity.