A study of the rate of inversion of sucrose in aqueous solutions of some strongly dissociated acids: primary kinetic salt effects and acidity constants

Abstract

The rate of inversion of sucrose has been studied for dilute aqueous solutions of several strong inorganic acids prepared by ion exchange from their alkali-metal salts. The acids were chloric, thiocyanic, methylsulphuric, methanesulphonic, and dithionic. Similar measurements have also been made with dilute solutions of three acids of intermediate strength, viz. sulphamic, hypophosphorous, and trichloroacetic, and a reliable value of the acidity constant K_a has been determined in each case. For an electrolyte of intermediate strength, the impossibility of fixing K_a independent of other parameters from a single type of measurement is emphasized. Previous determinations of the second dissociation constant of sulphuric acid from e.m.f. and kinetic measurements are compared, and the single set of parameter values which gives the best fit of all the data is determined.