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Enthalpies of Formation in the Pseudobinary LaAlxNi5-x System

Published

Author(s)

R Klein, P A. O'Hare, I Jacob

Abstract

The pseudobinary system LaAlxNi5-x has a composition limit at x {nearly equal to} 1.3. The standard molar enthalpies of formation fHm (298.15 K) were determined by solution calorimetry in HCl (c = 6 mol dm-3) to be -(129.4 +6.5) kJ mol-1 for x = 0.25; -(159.5 + 15.9) kJ mol-1 for x = 0.25; -(185.9 + 6.7) kJ mol-1 for x = 0.375; -(191.8 + 12.4) kJ mol-1 for x = 0.5; and (283.2 + 8.9) kJ mol-1 for x = 1. Previous results for δfHm (LaNi5) fall into two groups; they are compared with the present determination. The plot of δfHm against x is linear within experimental error. A minimum in the bond strength of Ni at x {nearly equal to} 0.2 shown by other techniques is not indicated by the δfHm s from the present measurements which, presumably, are not sufficiently sensitive to reveal it.
Citation
Journal of Chemical Thermodynamics
Volume
32
Issue
No. 12

Keywords

aluminum, enthalpy, lanthanum, nickel

Citation

Klein, R. , O'Hare, P. and Jacob, I. (2000), Enthalpies of Formation in the Pseudobinary LaAl<sub>x</sub>Ni<sub>5-x</sub> System, Journal of Chemical Thermodynamics (Accessed February 22, 2024)
Created December 1, 2000, Updated February 17, 2017