APPARENT MOLAR HEAT-CAPACITIES OF AQUEOUS-SOLUTIONS OF ACETIC, PROPANOIC AND SUCCINIC ACIDS, SODIUM-ACETATE AND SODIUM PROPANOATE FROM 300 TO 525 K AND A PRESSURE OF 28 MPA

The apparent molar heat capacities of dilute aqueous solutions of acet ic, propanoic and succinic acid and sodium salts of the two monofuncti onal acids were measured at 300 K < T < 525 K and p = 28 MPa. Correcti ons for ionization/ hydrolysis and relaxation effects were applied and the results were extrapolated to infinite dilution to calculate C-p,2 (o). After subtracting the heat capacity of a point mass, the remainin g heat capacity was successfully decomposed into functional group cont ributions at all temperatures. Together with the results of our previo us paper on alcohols and diols((2)) the heat capacity contributions of the CH2, CH3, OH, COOH, (COOH)2, and COONa groups are now available a nd these allow reasonably accurate predictions of the heat capacities of all compounds composed of these groups in this temperature range.