A STUDY OF THE RELATIVE BRONSTED ACIDITIES OF SURFACE COMPLEXES ON AG(110) Academic Article uri icon

abstract

  • The relative acidities of a number of Brnsted acids have been established on the Ag(110) surface under UHV conditions. For acids which react completely with adsorbed oxygen atoms on this surface to form H2O, relative acidities were determined by means of acid-base titration reactions. Adsorbed species such as carboxylates, alkoxides, etc., were formed by reaction of the parent acids with O(a) and then displaced from the surface by titration with stronger acids. Relative acidities of the acids which did not react to completion with O(a) were established on the basis of their relative extents of reaction. The relative acidity scale on Ag(110), according to the reaction BH(g) + B'(a) B'H(g) + B(a) was found to be HCOOH CH3COOH>C2H5OH> C2H2>CH3OH>C3H6, H2O>C2H4, C2H6, H2. This order is in excellent agreement with the acidity scale for these species in the gas phase according to BH(g)B-(g) + H+ (g); it cannot be explained by aqueous dissociation constants or homolytic bond dissociation energies. This result is in accord with the appreciable anionic character of the adsorbed species, since the electron affinity of the base, B, is a strong thermodynamic factor in the acidity in the gas phase. Both XPS and UPS results for adsorbed species on the Ag(110) surface are consistent with this interpretation. 1982.

published proceedings

  • SURFACE SCIENCE

author list (cited authors)

  • BARTEAU, M. A., & MADIX, R. J.

citation count

  • 73

complete list of authors

  • BARTEAU, MA||MADIX, RJ

publication date

  • August 1982