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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Melting point / freezing point

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Administrative data

Link to relevant study record(s)

melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Handbook of reliable peer-reviewed data
Principles of method if other than guideline:
No details are available on the guideline used to determine this result.
GLP compliance:
not specified
Type of method:
other: Unknown
Decomp. temp.:
480 °C
Remarks on result:
other: The atmospheric pressure at which this result was determined is not stated.
A decomposition temperature of 480°C is reported in a handbook of reliable data which has been subject to peer-review and in which the original data sources are traceable. The result is considered to be reliable.

Description of key information

Anhydrous form decomposes without melting at 480 ºC; Nonahydrate decomposes without melting at 400 ºC; Aqueous solution (40 %) -20 to -30 ºC

Key value for chemical safety assessment

Additional information


It should be noted that all the soluble iron salt category members decompose at elevated temperatures to give toxic gases. This is sometimes noticed as “sublimation”.

Ferric sulphate, Fe2(SO4)3

The anhydrous salt is solid to high temperatures, with a decomposition temperature of 480 ºC. The hydrated forms decompose at lower temperatures and the aqueous solution melts below 0 ºC.

Table: Melting points of the registered category member salt forms under standard pressure (ISO 5011, i.e. 101.3 kPa)

Category member, Molecular Formula  Anhydrous form Solid hydrate form Aqueous solution
Ferric sulphate, Fe2(SO4)3 480 °C (decomposes) Nonahydrate CAS 13520-56-4: 175 °C (loss of water), 400 °C (decomposition) -20 to -30 °C