Low-temperature heat capacity of tin dioxide: new standard data on thermodynamic functions

Abstract

The heat capacity of tin dioxide was measured at low temperatures by the adiabatic calorimeter technique. The measurements were conducted for two samples of tin dioxide. The discrepancy between two sets of the measurements does not exceed experimental error. However, a large disagreement (more than 5%) was observed between this study and data previously used for thermodynamic calculations. Using non-linear least-square method (LSM), the equation approximating and smoothing experimental data was derived. Thermodynamic functions at 298.15 K (heat capacity, entropy and enthalpy increment) values calculated from experimental data are as follows: C p, m 0=55.24±0.03 J mol −1 K −1, Δ 0 298S m 0=51.82±0.07 J mol −1 K −1, Δ 0 298H m 0=8.806±0.005 kJ mol −1. These values of the thermodynamic functions are about 5% larger than those used in reference books elsewhere.