6533b7d4fe1ef96bd12633d8
RESEARCH PRODUCT
Thermodynamics of hydronium and hydroxide surface solvation.
Carl CalemanJochen S. HubDavid Van Der SpoelGerrit GroenhofMaarten G. WolfPaul J. Van Maarensubject
HydroniumhydroxidekemiaInorganic chemistryThermodynamics010402 general chemistry01 natural sciencesIonSurface tensionchemistry.chemical_compound0103 physical scienceshydroksoniumPotential of mean forcePhysics::Chemical Physicsta116thermodynamiikka010304 chemical physicsHydrogen bondSolvationGeneral Chemistryhydronium0104 chemical scienceschemistry13. Climate actiontermodynamiikkaddc:540hydroksidiHydroxideSelf-ionization of waterdescription
[Introduction] The concentration of hydronium and hydroxide at the water-air interface has been under debate for a long time. Recent evidence from a range of experiments and theoretical calculations strongly suggests the water surface is somewhat acidic. Using novel polarizable models we have performed potential of mean force calculations of a hydronium ion, a hydroxide ion and a water molecule in a water droplet and a water slab and we were able to rationalize that hydronium, but not hydroxide, is slightly enriched at the surface for two reasons. First, because the hydrogen-bond acceptance capacity of hydronium is weaker than water it is more favorable to have the hydronium oxygen on the surface. Second, hydroxide ions are expelled from the surface of droplets, due to the entropy being lower when a hydroxide ion is hydrated on the surface. As a result, the water dissociation constant pK w increases slightly near the surface. The results are corroborated by calculations of surface tension of NaOH solutions that are in reasonable agreement with experiment. The structural and thermodynamic interpretation of hydronium and hydroxide hydration provided by these calculations opens the route to a better understanding of atmospheric- and surface chemistry. peerReviewed
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2014-01-01 |