The aqueous solubility of trichloroethene (TCE) and tetrachloroethene (PCE) as a function of temperature

Abstract

Using a flexible Au bag autoclave and a precision high-pressure liquid chromatography pump to control pressure, the liquid–liquid aqueous solubilities of TCE and PCE were measured as a function of temperature from 294 to 434 K (at constant pressure). The results were used to calculate the partial molal thermodynamic quantities of the organic liquid aqueous dissolution reactions: Δ Ḡ soln, Δ H̄ soln, Δ S̄ soln and Δ C̄ p soln. Calculated values for these quantities at 298 K for TCE are: Δ Ḡ soln=11.282 (±0.003) kJ/mol, Δ H̄ soln=−3.35 (±0.07) kJ/mol, Δ S̄ soln=−49.07 (±0.24) J/mol K, and Δ C̄ p soln=385.2 (±3.4) J/mol K. Calculated values for these quantities at 298 K for PCE are: Δ Ḡ soln=15.80 (±0.04) kJ/mol, Δ H̄ soln=−1.79 (±0.58) kJ/mol, Δ S̄ soln=−59.00 (±1.96) J/mol K and Δ C̄ p soln=354.6 (±8.6) J/mol K. These thermodynamic quantities may be used to calculate the solubility of TCE and PCE at any temperature of interest. In the absence of direct measurements over this temperature range, the Henry's Law constants for TCE and PCE have been estimated using the measured aqueous solubilities and calculated vapor pressures.