甲醛 Formaldehyde

物理描述 Physical Description

Solids containing varying amounts of formaldehyde, probably as paraformaldehyde (polymers of formula HO(CH2O)xH where x averages about 30). A hazard to the environment. Immediate steps should be taken to limit spread to the environment.

颜色/状态 Color/Form

Nearly colorless gas [Note: Often used in an aqueous solution]. /Pure formaldehyde/

气味 Odor

Pungent, suffocating odor

沸点 Boiling Point

-19.1 °C

熔点 Melting Point

-92 °C

闪点 Flash Point

185 °F (85 °C) (Closed cup) /Gas/

溶解度 Solubility

400000 mg/L (at 20 °C)

密度 Density

0.815 g/cu cm at -20 °C

蒸气密度 Vapor Density

1.067 (Air = 1)

蒸汽压力 Vapor Pressure

3,890 mm Hg at 25 °C /100% formaldehyde/

亨利常数 Henry'S Law Constant

Henry's Law constant = 3.37X10-7 atm-cu m/mol at 25 °C

稳定性/保质期 Stability/Shelf Life

On standing, especially in the cold, may become cloudy, and on exposure to very low temperature ppt of trioxymethylene formed; in air it slowly oxidizes to formic acid /40% solution/.

自燃温度 Autoignition Temperature

795 °F (424 °C)

分解 Decomposition

Uncatalyzed decomposition is very slow below 300 °C; extrapolation of kinetic data to 400 °C indicates that the rate of decomposition is about 0.44%/min at 101 kPa (1 atm). The main products are carbon monoxide and hydrogen. Metals such as platinium, copper, chromia, and alumina also catalyze the formation of methanol, methylformate, formic acid, carbon dioxide, and methane.

粘度 Viscosity

0.1421 cP at 25 °C

腐蚀性 Corrosivity

Aqueous formaldehyde is corrosive to carbon steel, but formaldehyde in gas phase is not.

燃烧热 Heat Of Combustion

570.7 kJ/mol (gas)

汽化热 Heat Of Vaporization

23.3 kJ/mol at 19 °C

表面张力 Surface Tension

27.3797 dyn/cm at 25 °C

电离电位 Ionization Potential

10.88 eV

气味阈值 Odor Threshold

Odor Threshold Low: 0.02 [ppm]; Odor Threshold High: 1.9 [ppm]; Odor threshold from CHEMINFO; In HSDB: odor threshold = 0.5-1 ppm; Odor threshold estimated at less than 0.5 ppm

折光率 Refractive Index

Index of refraction: 1.3746 at 20 °C/D /Formaldehyde soln/

解离常数 Dissociation Constants

13.3 (at 25 °C)

保留指数 Kovats Retention Index

229 ;273 ;247 ;247

其他实验性质 Other Experimental Properties

Specified gravity: 0.816 g at 20/20 °C /Formaldehyde, 37% uninhibited/

聚合 Polymerization

Anhydrous, monomeric formaldehyde ... /a dry gas/ is relatively stable at 80-100 °C but slowly polymerizes at lower temp. Traces of polar impurities such as acids, alkalies, and water qreatly accelerate the polymerization. When liquid formaldehyde is warmed to room temp in a sealed ampule, it polymerizes rapidly with the evolution of heat (63 kJ/mol or 15.05 kcal/mol).

辛醇/水分配系数 LogP

0.35

大气OH速率常数 Atmospheric Oh Rate Constant

9.37e-12 cm3/molecule*sec

氢离子浓度指数 pH

pH: 2.8 to 4.0 /Formaldehyde soln/

化学类 Chemical Classes

Other Classes -> Aldehydes