The dimensionless Henry’s law constant was determined for methyl tert-butyl ether (MTBE) at six temperatures (3,5, 10, 15, 20 and 25 C) by using a thermostatted flask (430 ml) containing an aqueous MTBE solution. The ratio
between the gas phase and the water phase in the flask was approximately 1.7:1. The aim of this study was to acquire data needed to model the behaviour of MTBE at groundwater conditions. The dimensionless Henry’s law constant at
10 C is approximately 0.01 but is 0.03 at 25 C. This is important for modelling MTBE because the variation of vaporization cannot be disregarded at groundwater temperatures. In a second experiment the water solubility of MTBE
was determined to be 62.1 g/l at 5 C and 35.5 g/l at 20 C). The high solubility at low temperatures could cause MTBE plumes from spills (fuel accidents etc.) to spread rapidly.