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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

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Physical & Chemical properties

Vapour pressure

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Description of key information

Value for assessment is set to 10^-6 Pa due to inorganic nature and decomposition before melting

Key value for chemical safety assessment

Vapour pressure:
0 Pa

Additional information

This endpoint is covered by the category approach for dissociating, inorganic and non-toxic iron compounds (please see the section summary for the category justification/report format).

Testing for this endpoint has been waived in accordance with column 2 and/or Annex XI, 2, restrictions as testing is technically not feasible.

Frost et al. (2006) used thermogravimetry under ambient pressure combined with mass spectrometry to study the thermal decomposition of a synthetic hydronium jarosite. Changes in the molecular structure were followed by infrared emission spectroscopy. Mass spectrometry through evolved gases confirmed the mass loss steps, which were observed at 262, 294, 385, 557 and 619 °C.

According to Frost et al. (2006) the first three mass loss steps involve the evolution of water vapour and are attributed to dehydroxylation. Therefore any measured vapour pressure would originate from the liberated water rather than actually represent a property of the submission item. In agreement with the guideline recommendation of ECHA (2008) the vapour pressure can be set to the very low value of 10^-6 Pa as no mercury or organometallic species are present in the submission item and the contained crystal water is not subject of the assessment. In conclusion the value for assessment is set to 10^-6 Pa.

  • ECHA European Chemicals Agency (2008). Guidance on information requirements and chemical safety assessment. Appendix R.7.13-2: Environmental risk assessment for metals and metal compounds. Guidance for the implementation of REACH. Version 1. Self-published, Helsinki, Finland, in July. 78 p.
  • Frost RL, Wills RA, Kloprogge JT, Martens WN (2006). Thermal decomposition of hydronium jarosite (H3O)Fe3 (SO4)2 (OH)6. DOI 10.1007/s10973-005-6908-0 Print ISSN 1388-6150 Online ISSN 1572-8943 Journal of Thermal Analysis and Calorimetry 83(1):213-8. URL