Registration Dossier

Environmental fate & pathways

Henry's Law constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The Henry's Law constant for NaTG was estimated as 8.992*10-6 Pa*m3/mol (8.875*10-11 atm*m3/mol) indicating that NaTG is expected to be essentially nonvolatile from water surfaces and that volatilization from moist soil surfaces may not occur.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
0
at the temperature of:
25 °C

Additional information

The Henry's Law constant was estimated according to the Handbook of Chemical Property Estimation Methods (Lyman, 1990) using the measured values of water solubility of NaTG and the measured value of vapour pressure of MeaTG. MeaTG can be used as a surrogate because the effect of a different counterion in an aqueous solution can be considered as low.

The Henry's Law constant [via Vp/Wsol estimate using the measured values from section 4.6 and 4.8] were calculated as follows:

H = 8.875*10-11 atm*m3/mol (8.992*10-6 Pa*m3/mol)

VP: 0.00036 mm Hg (IUCLID section: 4.6)

WS: 609 g/L (source: IUCLID section: 4.8)

The Henry's Law constant for NaTG was estimated as 8.992*10-6 Pa-m3/mol (8.875*10-11 atm*m3/mol) indicating that NaTG is expected to be essentially nonvolatile from water surfaces and that volatilization from moist soil surfaces may not occur. NaTG is not expected to volatilize from dry soil surfaces based upon an estimated vapour pressure of 0.048 Pa (3.6*10-4 mm Hg). The water solubility of NaTG was estimated as 609 g/L.

A pKa of 3.8 for thioglycolic acid also indicates that volatilization from water will not be an important environmental fate process as it will exist predominately in the ionic form under environmental pHs.