Determination of water in acetic and formic acids by the proton isoconcentration technique using the addition method

Abstract

Two analytical procedures have been used for the determination of water in acetic and formic acids under proton isoconcentration conditions, based on a large and systematic change in the potential measurements on addition of 0–2%m/m of water to a mixture of propylene carbonate and 10%V/V acetic or formic acid containing 2 × 10^–3M perchloric acid in glacial acetic acid as a background electrolyte, using a combination pH glass electrode. The first procedure was used directly for the determination of water in the range 0–10%m/m and the second for the range 10–100%m/m. In the second procedure the dilute acids were concentrated by mixing them with dry mixtures of propylene carbonate and acetic or formic acid. The method is fast, accurate and reproducible.