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Physical & Chemical properties

Vapour pressure

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Description of key information

Vapour pressure (tetramethyl orthosilicate): 1800 Pa at 25°C (EU Method A.4)
Vapour pressure (silicic acid): very negligible ((<1E-10 Pa Pa at 25°C, QSAR)

Key value for chemical safety assessment

Vapour pressure:
1 800 Pa
at the temperature of:
25 °C

Additional information

Several reliable data are available for tetramethyl orthosilicate. A measured vapour pressure value of 1300 Pa and 1800 Pa at 20°C and 25°C respectively were determined for the test substance using EU Method A.4 and in compliance with GLP. The result is considered reliable and selected as key study. In available supporting studies which are conducted using a generally acceptable scientific method, vapour pressure values of 4690 Pa and 1000 Pa at 20°C were determined for the substance. Also, the substance has a predicted vapour pressure of 890 Pa at 25°C. In a secondary source to which no reliability could be assigned, vapour pressure of 18 hPa at 20°C was reported for the substance. Differences in vapour pressure could be as a result of variation in the purity of the commercial samples tested and the method used. Tetramethyl orthosilicate is a moderately volatile substance.

Silicic acid has a negligible estimated vapour pressure of <1E-10 Pa at 25°C.

A measured vapour pressure of 12,790 Pa at 20°C is available for methanol (OECD, 2004a)