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Environmental fate & pathways

Henry's Law constant

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Description of key information

The HLC of 1,1-dichloroethylene has been calculated according to the equation R16-4 of ECHA guidance. 

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
2 572
at the temperature of:
20 °C

Additional information

The Henry's Law constant of 1,1 -dichloroethene has been calculated according to the equation R16 -4 of the guidance on information requirements and chemical safety assessment - chapter R16: environmental exposure assessment (ECHA 2012).

The equation used is the following :

HENRY = ( VP x MOLW ) / SOL

With :

VP = 66340 Pa at 20°C

MOLW = 96.94 g/mol

SOL = 2500 mg/L at 20°C.

The Henry's Law Constant has been calculated to be 2572 Pa.m3/mol (corresponding to 2.5 atm.m3/mol). Therefore, 1,1 -dichloroethylene is considered as highly volatile from water at 20°C.

Published data from handbook and HENRYWIN support this high volatility.

Additionally, data on the half-life of volatilisation of 1,1 -dichloroethene from water support this high HLC value as listed below :

- t1/2 = 27 min at 20°C (Dilling, 1977)

- t1/2 = 1.03h from river and 93.8h from lake (calculation of Episuite)