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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Diss Factsheets

Physical & Chemical properties

Stability: thermal, sunlight, metals

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Administrative data

Link to relevant study record(s)

Description of key information

Stable up to around 262 °C, after which decomposition commences

Additional information

Frost et al. (2006) investigated the thermal decomposition of a synthetic hydronium jarosite (EC 940-441-4). The scientific publication meets generally accepted standards. Thus the study is deemed conclusive and was rated „reliable with restrictions“, i.e. “Klimisch 2” according to the scale of Klimisch et al. (1997).

Thermogravimetry under ambient pressure combined with mass spectrometry was used to study the thermal decomposition under ambient pressure. Changes in the molecular structure of the hydronium jarosite were followed by infrared emission spectroscopy.

Five mass loss steps are observed at 262, 294, 385, 557 and 619 °C. Mass spectrometry through evolved gases confirmed the mass loss steps. Up to and including 385 °C evolution of water vapour, attributed to dehydroxylation, was the identified reason for the mass losses. At 557 °C, the sharp mass loss step 4, involved both the loss of water and the loss of sulphate (as sulphur trioxide) simultaneously. This mass loss step is ascribed to the loss of the hydrated proton and the loss of the associated sulphate unit. Eventually at 619 °C the remainder of the sulphate units was lost and both oxygen and sulphur dioxide were evolved.

In conclusion the substance was found thermally stable up to 262 °C. No melting or boiling occurs until complete decomposition. Absence of auto flammability and thermally induced explosivity was also shown.

  • 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
  • Klimisch HJ, Andreae M, Tillmann U (1997). A Systematic Approach for Evaluating the Quality of Experimental Toxicological and Ecotoxicological Data. DOI 10.1006/rtph.1996.1076 PMID 9056496 Regul Toxicol Pharmacol 25:1-5.

Justification for classification or non-classification

The following statement bases on DSD, the Commission Directive 2001/59/EC (28th ATP of Council Directive 67/548/EEC), and CLP (5th ATP of Regulation (EC) No 1272/2008 of the European Parliament and of the Council) as implementation of UN-GHS in the EU:

According to the available information no relevant instability of the submission item is considered and no indication for classification is given.