Effect of impurities on the critical temperature Tc at the upper critical end point of (cyclohexane + methanol)

Abstract

The effect exerted by small amounts of dissolved helium, nitrogen, argon, carbon dioxide, propane, n-hexane, and water on the critical temperature T c at the upper critical end point (UCEP) for (cyclohexane + methanol) was measured. Water had by far the greatest influence: dT c dx (H 2O) = 1280 K was found. The measured value: T c = (318.10±0.05) K, is lower than that obtained in all former measurements. In addition, the critical curve emanating from the UCEP was measured up to 33.6 MPa; it increases rapidly with temperature in the direction of high pressures.