LOW-TEMPERATURE HEAT CAPACITY OF WITHERITE BACO3(C)

Abstract

The heat capacity of witherite BaCO3 (c) as a function of temperature was experimentally studied in the interval 20.03-338.81 K and was calculated for temperatures below 20.03 K. At 298.15 K, the standard heat capacity, entropy, and enthalpy increment of witherite BaCO3(c) are as follows: Cp0(298.15 K) = 93.24 ± 0.17 J K-1 mol-1, S0(298.15 K) = 114.74 ± 0.45 J K-1 mol-1, H0(298.15 K) - H0(0 K) = 17.255 ± 0.064 kJ mol-1. In the temperature interval 195-255 K, the curve of witherite heat capacity shows an anomaly with entropy ΔanS = 0.37 J K-1 mol-1 and enthalpy ΔanH = 83 J mol-1.