Nitric acid, an important player in heterogeneous chemical processes occurring in tropospheric aerosols and polar stratospheric clouds, is a textbook example of a strong acid that dissociates essentially completely at low concentration in water.  Here we report first principles MD simulations of bulk HNO3 solutions over a range of concentrations, as well as HNO3 near the solution-air interface.  Our simulations reveal changes in the solvation of HNO3 that correlate well with spectroscopically measured changes in the degree of dissociation as a function of concentration, and at the interface vs. in bulk.  Our results suggest that the acidity of HNO3 decreases when its unprotonated oxygen atoms accept hydrogen bonds from water, which occurs in the bulk at high concentration, as well as when HNO3 is near the solution-air interface.

First-principles molecular dynamics studies of nitric acid in bulk aqueous solutions and at the air-water interface

242nd National Meeting (2011)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.