Heat capacity of potassium tungstates K2WnO3n+1 (n = 2, 3, 4) at temperatures from 273 K to 979 K

Compounds K2WnO3n+1 (n = 2, 3, 4) were synthesized using a pyrometallurgical technique. The products were characterized by X-ray diffraction analysis and found to be single-phase compounds. The enthalpy increments Delta(273.15 K)(T)H(m)degrees of each compound were measured by a drop method using a high-temperature Calvet calorimeter HT-1000 in the temperature range (273 to 979) K {or T = (273 to 878) K for K2W2O7}. The expression for molar hear capacity of each compound against temperature was obtained from experiment results. (C)1999 Academic Press.