Hydrogen

Melting point::

−259.2 °C(lit.)

Boiling point::

−252.8 °C(lit.)

Density :

0.0899

vapor density :

0.07 (21 °C, vs air)

vapor pressure :

Critical temperature is - 239.9 °C; noncondensible above this temperature

Flash point::

<-150°C

solubility :

1.6 mg/l (1 atm, 20 oc)

solubility :

slightly soluble in H2O

pka:

35(at 25℃)

appearance:

colorless gas

form :

colorless gas

color :

colorless gas; flammable

Odor:

Odorless gas

explosive limit:

74.2%

Water Solubility :

0.00017 g/100 mL

Merck :

13,4813

Dielectric constant:

1.0（100℃）

Stability::

Stable. Highly flammable. Readily forms explosive mixtures with air. Upper (U.K.) composition limit for use of a nitrogen/hydrogen mixture in the open lab is 5.7% hydrogen.

Symbol(GHS) 

GHS02,GHS04

Signal word 

Danger

Hazard statements 

H220-H280

Precautionary statements 

P210-P377-P381-P410+P403