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Environmental fate & pathways

Henry's Law constant

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Description of key information

The calculated Henry's Law constant is 7150 (1,3-butadiene) to 98200 (butane) Pa m³/mol

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
39 840
at the temperature of:
25 °C

Additional information

The Henry's Law constants for representative substances were: 1,3-butadiene: 7900 and 7150 Pa m³/mol, butane: 98200 and 85900 Pa m³/mol and 2–butene: 24300 and 15600 Pa m³/mol for bond contribution and group contribution methods respectively. The results have been calculated by a QSAR model with two modules recommended in ECHA (2008) Guidance on information requirements and chemical safety assessment R7a Endpoint specific guidance. The calculated values indicate that volatilisation from water is expected to occur at a rapid rate.

The mean of the Henry's Law values for the category is 39840 Pa m³/mol at 25°C and this has been used to complete the 'key value for chemical safety assessment'.