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Physical & Chemical properties

Vapour pressure

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Description of key information

Vapour pressure (substance): 18,600 Pa at 20°C
Vapour pressure (hydrolysis product): 0.05 Pa at 20°C (QSAR)

Key value for chemical safety assessment

Additional information

Several reliable measured vapour pressures are available, giving values of 174 - 202 hPa at 20°C. The key study (DIPPR 2003) was selected because it was obtained from extrapolation of a temperature-vapour pressure correlation using peer-reviewed measured data from a variety of sources over a wide range of temperatures (97.8 to 321.7°C) (DIPPR 2003). The result is in good agreement with a value of 190 hPa

based on interpolation from a temperature-vapour pressure correlation using measured vapour pressures in the range 5 -50°C (Wacker 2000). It is also in reasonable agreement with values of 174 hPa and 183 hPa at 20°C obtained by more limited extrapolations (Wacker 1995 and Wacker 1996), a static measurement of 202 hPa at 20°C and handbook values of 178 and 190 hPa at 20°C (SHC 1987 and CRC 1988) The results given in several other secondary sources, to which a reliability could not be assigned, show a range of 178 - 223 hPa. Variations in the vapour pressure values may be caused by variations in purity of the test substance and in the test method used. All values are of the same order of magnitude and consistent with the substance being highly volatile. The substance hydrolyses rapidly in contact with water. The vapour pressure of the silanol hydrolysis product, methylsilanetriol, has been estimated using a validated QSAR (Reconsile 2009).