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Henry's Law constant

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Description of key information

The Henry's Law  Constant of 0.00042 Pa m³/mol for TCPP was estimated from the ratio of its vapour pressure to its water solubility and the molecular weight at a temperature of 25 °C.

Key value for chemical safety assessment

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

Additional information

The Henry's law constant (HLC) is directly calculated as a ratio of the vapour pressure (Vp, 0.0014 Pa) to the water solubility (c, 1080 mg/l), which are experimentally determined at 25°C and 20°C, respectively. The molecular weight (MW, 327.57 g/mol) of TCPP was also used for estimation.

This value is supported by an estimation using the United States Environmental Protection Agency (US EPA) Estimation Programs Interface (EPI) Suite version 4.11.

The Henry´s law constant (HLC) of tris(2-chloro-1-methylethyl)phosphate , the main constituent of TCPP, was estimated to be

Bond estimation method:

HLC = 6.04E-03 Pa m3/mole

HLC = 5.96E-08 atm m3/mole

HLC = 2.44E-06 [unitless]

The bond method was chosen for this estimation instead of the group method because an independent evaluation of Altschuh et al. (1999) for a diverse set of organic chemicals found the bond method more accurate than the group method.

The value calculated via the measured vapour pressure and water solubility values of the regsitered substance TCPP was choosen as key value and taken for further assessment as this reflects measured values and the calculation mode is in line with the EU risk assessment.

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