ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Calorimetric enthalpies for reaction of hydrogen with niobium in the α-, and (α+α')-, α'-, (α'+β)-, (α+β)-, β- and (β+δ)-phase regions are reported. The free energies and entropies are reported for those regions where the equilibrium pressures can be measured. The enthalpies for reaction with (1/2)H2(g) in the plateau regions for (α+β) and (α+α') are −47.4 and −42.8 kJ/mol H, respectively. The magnitude of the calorimetric (absorption or desorption) enthalpy for the (β+δ) plateau region is 17.3 kJ/mol H which is about 3 kJ/mol H smaller than the literature value based on a van't Hoff plot of the decomposition pressures. This difference arises because of the large hysteresis in this system and because of the irreproducibility in the plateau pressures; neither factor affects the present calorimetrically determined enthalpies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.460404
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