VOLUME CHANGES OF IONIZATION OF ETHYLENEMALONIC ACID

Janez Cerar and Jože Škerjanc, Faculty of Chemistry and Chemical Technology, University of Ljubljana,1000 Ljubljana, Slovenia

ABSTRACT

Densities of aqueous solutions of 1,1-cyclopropanedicarboxylic acid (ethylenemalonic acid) have been determined at 25 ^oC for various degrees of neutralization of the acid. From the densimetric titration curve the apparent molar volume of undissociated acid, as well as the volume changes for ionization of the first and the second carboxylic group, DELTAV1 and DELTAV2, respectively, have been calculated. The resulting values at infinite dilutions, DELTAV1µ = -7.0 ml/mol COOH(1) and DELTAV2µ = -28.9 ml/mol COOH(2) are comparable to those found for other weak diprotic acids