Molecular and Equivalent Weights of the Organic Matter of a Podzol

Abstract

Abstract The number‐average molecular weights of the organic matter of the A 0 and B h horiozons of a Podzol, determined by freezing point depression in sulfolane, were 1684 and 669, respectively. From the molecular weights, in conjunction with ultimate and functional group analyses, molecular formulae were calculated. These were C 75 H 33 O 17 N 3 (COOH) 3 (OH) 12 (CO) 2 for the A 0 and C 21 H 12 (COOH) 6 (OH) 5 (CO) 2 for the B h organic matter. The presence of relatively large numbers of functional groups in the B h molecule offers interesting possibilities for metallo‐organic interactions. The equivalent weights of the same organic matter preparations, measured by discontinuous potentiometric titrations, were 165 for the A 0 and 76 for the B h organic matter. The ratio of molecular to equivalent weight was 10 for the A 0 and 9 for the B h material. These ratios were in both cases equal to the sum of carboxyl plus phenolic hydroxyl groups in the two molecules.