The pseudobinary system LaAlxNi5-x has a composition limit at x ≈ 1.4. The standard molar enthalpies of formation ΔfHmo(298.15 K) for this system were determined by solution calorimetry in HCl (c = 6 mol·dm−3 to be: -(129.4 ± 6.5) kJ·mol−1 for x = 0; -(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. Uncertainties correspond to twice the standard deviation of the mean and include contributions from the scatter of the calorimetric results and electrical calibrations, as well as analytical uncertainties. Previous results for ΔfHmo(LaNi5) fall into two groups; they are compared with the present determination. The plot of ΔfHmo against x is linear within experimental error.
- Formation enthalpy
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science (all)
- Physical and Theoretical Chemistry