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H‐ion Catalysis by Acid Clays and Exchange Resins
Author(s) -
McAuliffe Clayton,
Coleman N. T.
Publication year - 1955
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1955.03615995001900020011x
Subject(s) - chemistry , catalysis , potentiometric titration , inorganic chemistry , hydrolysis , ion , adsorption , ion exchange , ion exchange resin , diffusion , saturation (graph theory) , organic chemistry , physics , mathematics , combinatorics , thermodynamics
Except where complicated by the adsorption or the limited diffusion of the molecular reactant, rates of H‐ion catalyzed hydrolysis of ethyl acetate or inversion of sucrose were found to be proportional to the concentration of H‐ions in a variety of ion exchange systems. No correlation was found to exist between potentiometric H‐ion activities in clay or exchange resin suspensions and their efficiencies as catalysts. Not all acid clays were effective as H‐ion catalysts. On the basis of total acidity, Al‐clays had low catalytic activity. In general, for clays and resins partially saturated with metal cations, catalysis by non‐neutralized exchangeable H was as efficient as in the case of complete H‐saturation. It is suggested that effective ion concentrations in ion exchange systems are not the same for all reactions. The effective ion concentration approaches the total concentration for reactions between exchangeable ions and neutral molecules which are not limited by the diffusion rate of the molecular reactant. For reactions involving exchangeable ions and particles of opposite charge, the effective ion concentration approaches the concentration of the inter‐particle solution. In dispersed systems, potentiometric pH measures neither of these quantities.