Revised Thermochemistry of Gaseous Ammonium Nitrate, NH4NO3(g)

Abstract

In an earlier paper (Hildenbrand, D. L., Lau, K. H., and Chandra, D. J. Phys. Chem. B 2010, 114, 330.), we detected the presence of NH₄NO₃(g) in the vapor over the solid nitrate and evaluated its partial pressure along with those of HNO₃ and NH₃. The molecular constants of the gaseous nitrate were estimated in the absence of experimental values in an attempt to derive its enthalpies of sublimation and formation. After publication, we became aware of the sought molecular data, evaluated primarily from high-level theoretical calculations, and revised the analysis to yield Δ_fH₂₉₈^°(NH₄NO₃(g)) = −61.8 ± 5 kcal mol⁻¹.