Accession Number : AD0258695

Title :   ACID-BASE EQUILIBRIA IN ACETONITRILE. SPECTROPHOTOMETRIC AND CONDUCTOMETRIC DETERMINATION OF THE DISSOCIATION OF VARIOUS ACIDS

Corporate Author : MINNESOTA UNIV MINNEAPOLIS

Personal Author(s) : KOLTHOFF,I.M. ; BRUCKENSTEIN,S. ; CHANTOONI,M.K. JR.

Report Date : 01 MAY 1961

Pagination or Media Count : 1

Abstract : The indicators o-nitroaniline, o-nitro-pchloroaniline, and o-nitrodiphenylamine are about 50,000 times as strong in acetonitrile as in water. Perchloric acid behaves as a strong acid; other acids denoted by HA are weak. Except in extremely dilute solutions HBr, H2SO4, HNO3, and HCl dissociate yielding reversibly H(+) and AHA(-). The over-all dissociation constants of these acids were determined spectrophotometrically with the aid of indicator bases and conductometrically for H2SO4 and picric acid. By other suitable methods the stability constants, (K sub AHA(-) equal (AHA(-)/(HA) (A (-)), were evaluated. The value of K sub AHA(-) decreases from 1300 for H2SO4 to 250 for HBr, and 200 for HNO3 and HCl at 25 C. The following values pK sub HA are reported: HBr, 5.5; H2SO4, 7.25; and HNO3 and HCl, 8.9. Picric acid at concentrations smaller than 0.1 M dissociates into H(+) and Pi(-), and pK sub HPi(--) equals 8.9. The ion pair dissociation constants of tetraethylammonium bisulfate and of lithium nitrate were found to be 0.0014 and 0.00041, respectively.

Descriptors :   *ACID BASE EQUILIBRIUM, *ACIDS, *CHEMICAL EQUILIBRIUM, *DISSOCIATION, *ORGANIC ACIDS, ACETONITRILE, BROMIDES, CHEMICAL INDICATORS, DETERMINATION, ELECTRICAL CONDUCTIVITY, HYDROCHLORIC ACID, HYDROGEN COMPOUNDS, NITRIC ACID, NITRO RADICALS, PERCHLORIC ACID, PHENOLS, SOLUTIONS(MIXTURES), SPECTROPHOTOMETERS, SULFURIC ACID

Distribution Statement : APPROVED FOR PUBLIC RELEASE