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Environmental fate & pathways

Henry's Law constant

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Reference
Endpoint:
Henry's law constant
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Principles of method if other than guideline:
Henry's Law constant was calculated from the ratio of the vapour pressure to the water solubility following the Equation R16-4 reported in the ECHA Guidance on Information Requirements and Chemical Safety Assessment_ Chapter R.16: Environmental Exposure Estimation_ Version 3.0, February 2016.
Key result
H:
147 592 Pa m³/mol
Temp.:
25 °C
Atm. press.:
101 325 Pa
Remarks on result:
other: calculated
H:
1.46 atm m³/mol
Temp.:
25 °C
Atm. press.:
1 atm
Remarks on result:
other: calculated

As Hexafluorobutadiene is a gas at room temperature volatilisation from aqueous medium is expected to be rapid.

The Henry’s Law Constant can be determined by calculation using the ratio of the vapour pressure to the water solubility as stated in the equation R16-4 (ECHA guidance R16, version 3.0, February 2016)

 

HLC = (Vapour Pressure * Molecular Weight) / Water Solubility

 

With:

VP in Pascal

MW g/mol

Water solubility in mg/L

 

Since Hexafluorobutadiene is a gas at room temperature/atmospheric pressure, its vapour pressure is greater than the atmospheric pressure.

Henry's Law constant was thus calculated using the experimental value for water solubility of 230.5 mg/l at 20°C.

MW: 162.03 g/mol.

HLC = 2.01*10+5 (Pa) x 162.03 (MW) / 230.5 g/m3=147592 Pa.m3.mol-1or 1.46 atm.m3.mol-1

Conclusions:
The Henry's Law constant was calculated for Hexafluorobutadiene at 20°C:
HLC = 147592 Pa m3/mol

Description of key information

The Henry's Law Constant was estimated by calculation using the experimental value available for water solubility at 20°C.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
148 000
at the temperature of:
25 °C

Additional information