Measurement approach of interfacial tension on example of water-toluene

A quite simple experimental method for interfacial tension determination is presented. It is based on measurements done in the digital photographs of the drops at the creation moment. It is validated with the result of other researchers. The interfacial tension for water-toluene interface is obtained in the range 0.1°C–96.6°C. It is almost constant up to 40°C. Then appear linear decrease to 80°C. Next is observed sharp drop to 96.6°C. Uncertainties of the determined values are estimated. A gaseous phase occurs at temperature close to the boiling point, thus interfacial tension was not determined. The experimental results are presented with a rational function.