Acid-Base Equilibria in Aqueous and Nonaqueous Solutions
For uncharged proton acids in basic solvents of not too low dielectric constant the reaction .........(1) takes place, the extent of the reaction depending on the strength of the acid relative to the basic strength of the solvent S. The equilibrium constant for this reaction .........(2) is usually expressed as the more commonly used dissociation constant which includes the concentration of the solvent. ......(3) The constant varies with ion concentration, and in the limited range of concentration where the Debye-Hückel theory applies the following equation may be used to determine the thermodynamic equilibrium constant .......(4) where The values for A at 25 C. are: for water (dielectric constant ) 1.020, for methyl alcohol () 4.02, for ethyl alcohol () 5.97, and for butyl alcohol () 9.79. For more concentrated solutions no theoretical equation can be given, but Table I shows that the change in the equilibrium constant is of considerable magnitude.
Professor of Chemistry, University of Pennsylvania, Philadelphia, Pa.
Paper ID: STP47879S
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