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Enthalpies of Formation in the Pseudobinary LaAlxNi5-x System



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


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.
Journal of Chemical Thermodynamics
No. 12


aluminum, enthalpy, lanthanum, nickel


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