Sulphur trioxide

Melting point / freezing point

Link to relevant study record(s)

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:

data from handbook or collection of data

Guideline:

other: Not reported

Type of method:

other: Not reported

Key result

Melting / freezing pt.:

16.8 °C

Atm. press.:

ca. 101 325 Pa

Conclusions:

The melting point of sulphur trioxide is 16.8 °C

Executive summary:

The melting point of sulphur trioxide is reported to be 16.8 °C. However, it should be noted that the different polymerised forms of the substance have different melting points: α form (62.4 °C), β form (32.5 °C), γ form (16.8 °C). Melted sulphur trioxide usually exists in the γ form.

Description of key information

The melting point of sulphur trioxide is reported to be 16.8 °C. However, it should be noted that the different polymerised forms of the substance have different melting points: α form (62.4 °C), β form (32.5 °C), γ form (16.8 °C). Melted sulphur trioxide usually exists in the γ form.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

16.8 °C