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Physical & Chemical properties

Melting point / freezing point

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Reference
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
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
Decomposition:
yes
Decomp. temp.:
480 °C
Sublimation:
no
Remarks on result:
other: The atmospheric pressure at which this result was determined is not stated.
Conclusions:
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

“Sublimation”

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