caa a22 4500 477139183 CHVBK 20180405111727.0 cr unu---uuuuu 170330e19971201xx s 000 0 eng 10.1023/A:1022977006327 doi (NATIONALLICENCE)springer-10.1023/A:1022977006327 Thermodynamic Properties of Aqueous Dimethylamine and Dimethylammonium Chloride at Temperatures from 283 K to 523 K: Apparent Molar Volumes, Heat Capacities, and Temperature Dependence of Ionization [Elektronische Daten] [Dmitri Shvedov, Peter Tremaine] Data for the apparent molar volumes of aqueous dimethylamine and dimethylammonium chloride have been determined with platinum vibrating tube densimeters at temperatures 283.15 K ≤ T ≤ 523.15 K and at different pressures. Apparent molar heat capacities were measured with a Picker flow microcalorimeter over the temperature range 283.15 K ≤T ≤ 343.15 K at 1 bar. At high temperatures and steam saturation pressures, the standard partial molar volumes $$V_2^ \circ $$ of dimethylamine and dimethylammonium chloride deviate towards positive and negative discontinuities at the critical temperature and pressure, as is typical for many neutral and ionic species. The revised Helgeson-Kirkham-Flowers (HKF) model and fitting equations based on the appropriate derivatives of solvent density have been used to represent the temperature and pressure dependence of the standard partial molar properties. The standard partial molar heat capacities of dimethylamine ionization $$\Delta _{{\text{ion}}} C_{{\text{p,2}}}^ \circ $$ , calculated from both models, are consistent with literature data obtained by calorimetric measurements at T ≤ 398 K to within experimental error. At temperatures below 523 K, the standard partial molar volumes of dimethylamine ionization $$\Delta _{{\text{ion }}} V_2^ \circ $$ agree with those of morpholine to within 12 cm3-mol-1, suggesting that the ionization of secondary amine groups in each molecule is very similar. The extrapolated value for $$\Delta _{{\text{ion }}} V_2^ \circ $$ of dimethylamine above 523 K is very different from the values measured for morpholine at higher temperature. The difference is undoubtedly due to the lower critical temperature and pressure of (CH3)2NH(aq). Plenum Publishing Corporation, 1997 Partial molar heat capacities nationallicence partial molar volumes nationallicence dimethylamine nationallicence dimethylammonium chloride nationallicence hydrothermal nationallicence aqueous amine solutions nationallicence Shvedov Dmitri Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1C3X7, Canada aut Tremaine Peter Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1C3X7, Canada aut Journal of Solution Chemistry Kluwer Academic Publishers-Plenum Publishers 26/12(1997-12-01), 1113-1143 0095-9782 26:12<1113 1997 26 10953 https://doi.org/10.1023/A:1022977006327 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1022977006327 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shvedov Dmitri Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1C3X7, Canada aut NATIONALLICENCE 700 1- Tremaine Peter Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1C3X7, Canada aut NATIONALLICENCE 773 0- Journal of Solution Chemistry Kluwer Academic Publishers-Plenum Publishers 26/12(1997-12-01), 1113-1143 0095-9782 26:12<1113 1997 26 10953 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer