ASPER wrote:
oh and another thing,lol, i was going to eat and while washing my hands i thought of the hydrogen and iron atom and remembered that the metal swells and there was doubt if the swelling was due to hydrogen inside the iron in space but not bonding the both atom together,and the article you show me it does not say they bond ,the iron just swells "The researchers think the hydrogen settles into octahedral spaces between the iron atoms, altering their bonds and causing the sample to swell" they settle bettwen the iron bonds but do not join together(iron and hydrogen).
peace
That artical was old the first metioned of Iron hydride I know of. This is a x-ray crystallography experiment showing the hydrogen was not merely disolved in the iron.
http://cat.inist.fr/?aModele=afficheN&cpsidt=13412441Quote:
Titre du document / Document title
Thermodynamic properties of iron hydride
Auteur(s) / Author(s)
TKACZ M. (1) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, POLOGNE
Résumé / Abstract
X-Ray diffraction studies of the iron sample subjected to high hydrogen pressure inside a diamond anvil cell have been carried out in order to determine the equilibrium conditions of formation and decomposition of the iron hydride. Due to hysteresis, commonly observed in transition metal hydrides, the pressure of decomposition of the corresponding hydride describes the equilibrium as decomposition is considered to be a stress-free process. X-Ray diffraction studies have revealed the structural phase transition from the b.c.c. structure of iron metal to the d.h.c.p. of hydride at 3.5 GPa, while the decomposition process has been observed at a hydrogen pressure of about 2.2 GPa. Both processes are accompanied by a volume change of the host lattice of 2.8 Å[3] as compared to the volume of hexagonal iron, extrapolated from high pressure. Free enthalpy of formation of iron hydride was calculated as equal to 23.5 kJ/mol of hydride. Assuming the entropy of formation of 52.25 J/mol/K, enthalpy of iron hydride is positive and equals to 7.9 kJ/mol of FeH.
Revue / Journal Title
Journal of alloys and compounds (J. alloys compd.) ISSN 0925-8388
Source / Source
2002, vol. 330-32, pp. 25-28 (15 ref.)
Langue / Language
Anglais
Editeur / Publisher
Elsevier, Lausanne, SUISSE (1991) (Revue)
Mots-clés anglais / English Keywords
Transition metal alloy ; Experimental study ; Iron hydride ; Enthalpy ; Entropy ; Heat of formation ; Hexagonal lattices ; Phase transformation ; Hysteresis ; Diamond anvil ; Pressure effect ; X ray diffraction ; Thermodynamic properties ;
Mots-clés français / French Keywords
Métal transition alliage ; Etude expérimentale ; Fer hydrure ; Enthalpie ; Entropie ; Chaleur formation ; Réseau hexagonal ; Transformation phase ; Hystérésis ; Enclume diamant ; Effet pression ; Diffraction RX ; Propriété thermodynamique ;
001d11f ; 240 ;
07 Feb 2007, 8:41 pm
