Formation Of Hydronium Ion Research Articles

On-line measurement of the absolute humidity of air, breath and liquid headspace samples by selected ion flow tube mass spectrometry.

We describe how selected ion flow tube mass spectrometry (SIFT-MS) can be used to determine the absolute humidity of air, breath and liquid headspace samples. This involves the determination of the relative count rates of the H3O+ ions and those H3O+.(H2O)(1,2,3) hydrate ions that inevitably form in the helium carrier gas when humid samples are being analysed by SIFT-MS using H3O+ precursor ions. This requires an understanding of the kinetics of hydrated hydronium ion formation, the involvement of mass discrimination in the analytical quadrupole mass spectrometer and the decreased diffusive loss of the heavier hydrates along the flow tube. Thus, we show that the humidity of breath and liquid headspace samples, typically at the few percent level, can be directly obtained on-line to the SIFT-MS instrument along with the concentrations of trace gases, which are present at much lower levels. We emphasise the value of parallel humidity measurements in ensuring good real-time sampling of breath and liquid headspace and the value of such measurements to trace gas analysis using SIFT-MS.

Absence of Hydronium Ion Formation in a Ternary Crown Ether·Mineral Acid·Water Complex: X-ray Crystal Structure of 1,8-Oxybis(ethyleneoxyethyleneoxy)anthracene-9,10-dione·HNO3·3H2O

The X-ray crystal structure of 1,8-oxybis(ethyleneoxyethyleneoxy)anthracene-9,10-dione, 1, in the presence of nitric acid and water has been determined. The structure indicates the complex can be described principally as 1·HNO3·2H2O (only two water molecules in contact with the acid), as opposed to [H5O2·1]+NO3-, where the proton has been transferred to water to from a higher-order hydronium ion. Formation of a solid-state, strong mineral acid adduct without hydronium ion formation has not been previously observed.

Coadsorption of water and hydrogen on Pt(100): formation of adsorbed hydronium ions

Coadsorption of water and hydrogen on Pt(100) was studied under conditions of ultrahigh vacuum with thermal desorption spectroscopy and high resolution electron energy loss spectroscopy. The experiments were conducted over a temperature range of 100–700 K and coverages ranging from submonolayer to several multilayers. The surface reaction H 2O + H → H 3O + + e − occurs in water/hydrogen coadsorbate; H 2O + was identified by a new vibrational peak at 1150 cm −1, assigned to the umbrella mode, and isotope exchange between coadsorbed H 2O and D. Isotope exchange in the coadsorbate involves three reaction equilibria: intralayer exchange in the aqueous layer (primarily water), intralayer exchange in the chemisorbed deuterium layer, and interlayer exchange between the aqueous and chemisorbed deuterium layers. Both intralayer exchanges are essentially completely equilibrated for the conditions of the experiment, whereas interlayer exchange is kinetically limited, ranging from zero to 55% approach to equilibrium depending on the coverages of both species. Irreversible hydration of chemisorbed hydrogen, as probed by thermal desorption, is essentially negligible. This behavior is consistent with the production of hydronium ions, since the above surface reaction is approximately energetically neutral. These results are also consistent with recent attempts to unify the electrochemical and vacuum potential scales, which predict hydronium ion formation on high work function surfaces, like platinum, but not on low work function surfaces, like copper.

Complex formation of hydronium ion with several crown ethers in 1,2-dichloroethane, acetonitrile, and nitrobenzene solutions

A conductance study concerning the interaction between hydronium ion and several crown ethers in acetonitrile, nitrobenzene and 1,2-dichloroethane solutions has been carried out at 25°C. The stability constants of the resulting 1:1 complexes in acetonitrile and nitrobenzene solutions were determined from the molar conductance-mole ratio data and found to vary in the order 18C6>DB30C10>DC18C6>DB18C6>DB21C7>DB24C8>B15C5. In 1,2-dichloroethane solution, the complexation process results in the dissociation of ion pairs. There is an inverse relationship between the stabilities of the complexes and the Gutmann donicity of the solvents. In nitrobenzene solution, some evidence for the formation of a 2:1 sandwich adduct between the smaller crowns (i.e., B15C5 and 18-crowns) are observed from the molar conductance-mole ratio data which is supported by the1H NMR data.

Formation of hydronium ions on Brønsted sites in zeolitic catalysts: a quantum-chemical ab initio study

A new structure for the surface complex of water on bridged hydroxyl sites is proposed which is stablized by two hydrogen bonds. The energy for the formation of a surface hydronium is estimated to be 0.5±20 kJ/mol. This conclusion is based on quantum-chemical ab initio SCF calculations (DZP basis set, geometries optimized) on the complex of water with the H 3SiOH-Al(OH) 2OSiH 3 model of a bridged hydroxyl site and on the complex of the hydronium ion with the [H 3SiOAl(OH) 2OSiH 3]-model of a negatively charged framework site. Electron-correlation contributions are estimated by the MP2 method on smaller models (SiH 3 groups replaced by H). For the latter models, second energy derivatives are also obtained. A direct SCF code was employed on workstations.

Nonionic surface-active compounds. V. Effect of electrolyte

The effect of electrolyte on the micellar properties in aqueous solution of a series of polyoxyethylene derivatives of lauryl and tridecyl alcohols, and of nonyl phenol, has been studied. Changes in the critical micelle concentration and micellar size have been followed as a function of concentration of various electrolytes. The critical micelle concentration (c.m.c.) is lowered in a way comparable with that observed with ionic surface-active agents, but there is little increase in micellar size, except with the least soluble compounds. With more soluble compounds, in fact, there appears to be a slight decrease in micellar size. Many of the data can be explained in terms of a positive double layer charge arising from hydronium ion formation.