| Popis: |
The nature of the ions present in mixtures of trialkylamines (B) with carboxylic acids (HA) is discussed. New ab initio molecular dynamics (AIMD) simulations of mixtures of triethylamine (TEA) with acids here reveal the same cation type, the large complex [B(HA)nHB]+, as seen earlier with pyridine (PYR). Since this indicates that the ionization equilibrium reaction 2 B(HA)n ⇄ B(HA)nHB+ + A(HA)n-1 − is perhaps more general than for pyridine systems, a new analysis derives ∆G for this equilibrium reaction from experimental conductivities, viscosities, and densities, as a function of xB (mole fraction of B in the acid/base mixture). The results show that large Walden constant values, which might be indicative of Grotthuss H+ conductivity mechanisms, are not needed except for formic-acid-rich mixtures. |
