Abstract: The molar heat capacities (Cp,m) of crystalline potassium dichromate (K2Cr2O7) were measured with a precision automated adiabatic calorimeter over the temperature range from 100 K to 390 K. No phase transition or other thermal anomaly was observed in this temperature region. However, it was found that the relationship of Cp,m with respect to temperature T is different in different temperature regions. The polynomial functions of Cp,m vs. T were established in different temperature regions based on the heat capacity measurements by means of the least-fitting square method. These functions are as following: for 100 K ≤ T ≤ 275 K, Cp,m=0.0050T2－1.0320T＋125.22 (J•K－1•mol－1)；for 275 K ≤ T ≤ 350 K, Cp,m=209.37 J•K－1•mol－1；for 350 K ≤ T ≤390 K, Cp,m=0.0266T2－18.823T＋3542.3 J•K－1•mol－1.According to the relationship of Cp,m vs. T and thermodynamic equations, the values of thermodynamic function of potassium dichromate were calculated in the temperature range of 298.15～400.15 K with 5 K intervals.

Key words: Potassium dichromate (K₂Cr₂O₇), Low-temperature heat capacity, Thermodynamic function, Adiabatic calorimetry