Register      Login
Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Proton-Coupled Transport of Ammonia in Aqueous Hydrochloric Acid

DG Leaist

Australian Journal of Chemistry 38(2) 249 - 260
Published: 1985

Abstract

Ternary diffusion in aqueous ammonia + hydrochloric acid solutions has been measured at 25°C. It is shown that the transport coefficients can be successfully predicted from the mobilities of H+, Cl -, NH4+, and un- ionized ammonia species present in the solutions. When an ammonia concentration gradient is prepared in a solution containing excess acid, the region of the solution with the higher ammonia concentration is depleted in H+ by formation of ammonium ion: NH3+H+ ↔ NH4+. As highly mobile H+ diffuses up the ammonia gradient, there is counterflow of NH4+ in order to maintain electroneutrality . This mechanism leads to rapid diffusion of the ammonia component as NH4+. Binary diffusion coefficients of aqueous ammonia have also been measured. Extrapolation gives 2.08(±0.01) × 10-2m2 s-1 for the limiting diffusion coefficient of un-ionized ammonia, a value 6% greater than the limiting diffusion coefficient of the ammonium ion.

https://doi.org/10.1071/CH9850249

© CSIRO 1985

Committee on Publication Ethics


Export Citation Get Permission

View Dimensions