Hydrogen

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Other names/abbreviations:

H

Element no:	1
Element group:	1 (IUPAC) I A (American labelling) I A (European labelling) Alkali metals
Element type:	Nonmetals
CAS-Number:	1333-74-0
EINECS-Number:	215-605-7

Chemical properties

Reaction of hydrogen with metals/metal ions
Cd usually does not react with H₂ (g). At 450°C H₂ is adsorbed in the metal. When the metal has reached max. adsorption the temperature will increase and Cd reacts with H₂ [4].

Cd (s) + H₂ (g) CdH (s) + H·


Solubility
Water: 1.6 mg/l (20 °C) [2]

Safety

Symbol: F+
R-phrases: 12
S-phrases: 9-16-33

Physical properties

Appearance
	Physical state @ 20°C:	Gas [2]
	Color:	Colourless [2]
	Odor:	None [1]

Bulk properties

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	Molecular weight (g/mol):	1.00794(7) [1]
	Melting point (°C):	-259.193 (H2) [1] -254.42 (D2) [1] -252.53 (T2) [1]
	Boiling point (°C):	-252.76 (H2) [1] -249.48 (D2) [1] -248.11 (T2) [1]
	Ignition temperature (°C):	560 [2]
	Flash point (°C):	-240 [2]
	Explosion limits (vol. %):	4-77.0 [1]
	Density (g/cm3):	0.00007 [2]
	Molar volume (cm3):	65 (Critical) [3]

Optical properties
	Refractive index:	1.000132 (g) 1.12 (l)

Thermodynamic properties
	ΔfH°gas (kJ/mol):	217.998 ± 0.006 (H) [1] 0 (H2) [1] 221.62 (D) [1] 0 (D2) [1] 0.33 (HD) [1]
	ΔH°fusion (kJ/mol):	0.117 (H2) [1] 0.197 (D2) [1] 0.250 (T2) [1]
	ΔH°vaporization (kJ/mol):	0.904 (H2) [1] 1.226 (D2) [1] 1.393 (T2) [1]
	S°gas (J/K·mol):	1114.717 ± 0.002 (H) [1] 130.680 ± 0.003 (H2) [1] 123.24 (D) [1] 144.85 (D2) [1] 143.69 (HD) [1]
	ΔfG°gas (kJ/mol):	203.26 (H) [1] 0 (H2) [1] 206.52 (D) [1] 0 (D2) [1] -1.46 (HD) [1]
	Cp (gas) (J/K·mol):	20.786 (H) [1] 28.82 (H2) [1] 28.836 (H2, 25 °C) [3] 20.786 (D) [1] 29.20 (D2) [1] 29.20 (HD) [1]
	Critical temperature (°C):	-239.96 (H2) [1] -234.8 (D2) [1] -232.55 (T2) [1]
	Critical pressure (Pa):	1293000 (H2) [3]

Electronic properties
	Electron configuration:	1s1

References

1: Greenwood,N.N., Earnshaw,A. Chemistry of the elements
2nd edition (1997) Edited by Greenwood,N.N., Earnshaw,A. pp. 1-1340, Butterworth-Heinemann. Oxford. Great Britain

2: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5

3: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA

4: Gmelin Handbuch der anorganischen Chemie Erg. 33 (1958)

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© Michael Pilgaard
Created: September 29, 2008
Last update: October 10, 2008