
%0 Journal Article
%A Leaist, DG 
%T Proton-Coupled Transport of Ammonia in Aqueous Hydrochloric Acid
%J Australian Journal of Chemistry
%D 1985/02/01
%V 38
%N 2
%P 249-260
%K 
%R https://doi.org/10.1071/CH9850249
%U https://www.publish.csiro.au/paper/CH9850249 
%X Ternary diffusion in aqueous ammonia + hydrochloric acid solutions has been measured at 25&#176;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+ &#8596; 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) &#215; 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. 
