Surface tension and molar surface free energy and entropy of water to -27.2 °C

To remove a deficiency in the growing data base on supercooled water, the surface tension of water has been measured, using a small-sample capillary rise method, down to -27.2 °C. The data do not accord with extrapolations of equations best fitting data above 0 °C but show a more rapid increase with decreasing temperature. This distinguishes water from other hydrogen-bonded fluids and focuses attention on weaknesses of classical interpretations of the temperature dependence of the surface tension. The observations are related to recent molecular dynamics studies of water surface tension. The possibility of an artifact in experimental studies, caused by anomalous gas solubility in the supercooled regime, is recognized.