Hon Chung Ko

Thermodynamic properties of CF and CF2 from molecular flow effusion and mass spectrometer investigations

The reaction of CF4 and C has been studied in the temperature range 1800–2500 K. Equilibrium data were obtained for species obtained in this temperature range by two techniques: (i) molecular flow effusion and (ii) effusion-mass spectrometry. Heats of formation were calculated from the reaction thermodynamics for the species CF(g), ΔH°f298 K= 58 ± 1 kcal/mol, and CF2(g), ΔH°f298 K=–41.7 ± 0.4 kcal/mol (third law). The S°298 of CF2(g) is 58.9 ± 1.2 cal/deg. mol (second law). Calculations provided thermodynamic limits for the species CF3(g) and C2F2(g).

Enthalpy of formation of aqueous tungstate ion and of crystalline tungstic acid (H2WO4)

Abstract Calorimetric measurements of the enthalpy of reaction of WO 3 (c) with excess OH − (aq) have been made at 85°C. Similar measurements have been made with MoO 3 (c) at both 85 and 25°C, to permit estimation of Δ H °=−13.4 kcal mol −1 for the reaction WO 3 (c)+2OH − (aq)=WO 2− 4 (aq)+H 2 O(liq) at 25°C. Combination of this Δ H ° with Δ H ° f for WO 3 (c) leads to Δ H ° f =−256.5 kcal mol −1 for WO 2− 4 (aq). We also obtain Δ H ° f =−269.5 kcal mol −1 for H 2 WO 4 (c). Both of these values are discussed in relation to several earlier investigations.