Melting point :16.8 °C(lit.)
Boiling point :44.8 °C
Density :1.97 g/mL at 25 °C(lit.)
vapor density :2.8 (vs air)
vapor pressure :280 mm Hg ( 25 °C)
storage temp. :Indoors
solubility :reacts with H2O
form :colorless liquid
color :white needles
Water Solubility :reacts violently
Merck :13,9069
Dielectric constant :3.1（18℃）
Stability :Stable. Incompatible with organic materials, finely powdered metals, bases, water, cyanides and a wide variety of other chemicals. Reacts violently with water, oxygen and other chemicals - read a full data sheet before use.
CAS DataBase Reference :7446-11-9(CAS DataBase Reference)
NIST Chemistry Reference :Sulfur trioxide(7446-11-9)
EPA Substance Registry System :Sulfur trioxide (7446-11-9)

Symbol(GHS):
Signal word:	Danger
Hazard statements:	Code Hazard statements Hazard class Category Signal word Pictogram P-Codes H314 Causes severe skin burns and eye damage Skin corrosion/irritation Category 1A, B, C Danger P260,P264, P280, P301+P330+ P331,P303+P361+P353, P363, P304+P340,P310, P321, P305+ P351+P338, P405,P501 H335 May cause respiratory irritation Specific target organ toxicity, single exposure;Respiratory tract irritation Category 3 Warning
Precautionary statements:	P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P280 Wear protective gloves/protective clothing/eye protection/face protection. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P310 Immediately call a POISON CENTER or doctor/physician.