Keith G. McCurdy

Apparent molar heat capacities and volumes of aqueous electrolytes: CaCl2, Cd(NO3)2, CoCl2, Cu(ClO4)2, Mg(ClO4)2, and NiCl2

We have used a flow calorimeter and a flow densimeter for measurements leading to apparent molar heat capacities and apparent molar volumes of six 2∶1 electrolytes in aqueous solution at 25°C. Results of these measurements have been used to derive apparent molar heat capacities and volumes at infinite dilution for all six electrolytes: CaCl2, Cd(NO3)2, CoCl2, Cu(ClO4)2, Mg(ClO4)2, and NiCl2.

Heat capacities of aqueous nitric acid, sodium nitrate, and potassium nitrate at 298.15 K: ΔCpo of ionization of water

Abstract We have made calorimetric measurements leading to apparent molar heat capacities at constant pressure of dilute aqueous solutions of HNO 3 , NaNO 3 , and KNO 3 at 298.15 K. Results have been used to derive C p , φ o = −72.1 J K −1 mol −1 for HNO 3 (aq), C p , φ o = −28.9 J K −1 mol −1 for NaNO 3 (aq), and C p , φ o = −59.8 J K −1 mol −1 for KNO 3 (aq). These C p , φ o values are combined with others previously published to obtain a “best” ΔC p o = −215 J K −1 mol −1 for ionization of water at 298.15 K.

Heat capacities of aqueous perchloric acid and sodium perchlorate at 298°K: ΔC p o of ionization of water

We have used a Picker flow calorimeter for measurements leading to apparent molal heat capacities of dilute aqueous solutions of HClO4 and NaClO4 at 298°K. Results have been used to derive φc°=−27.1J-°K−1-mole−1 for HClO4 (aq.), φc°=15.2J-°K−1-mole−1 for NaClO4 (aq.), and ΔCp=−213.8J-°K−1-mole−1 for ionization of water.

Glass-electrode measurements over a wide range of temperatures: The ionization constants (5–90°C) and thermodynamics of ionization of aqueous benzoic acid

Glass-electrode measurements have been applied to the determination of the ionization constant of aqueous benzoic acid from 5 to 90°C, with the experimental procedure and calculations described in detail. The results lead to ΔHo=+60 cal-mole−1 for the standard enthalpy of ionization at 298°K, which is compared with ΔHo values from earlier investigations.

Heats of melting of sodium nitrate and indium by differential scanning calorimetry: a suggestion for a new calibration substance

Abstract Measurments with a Perkin-Elmer DSC-2 differential scanning calorimeter that has been calibrated with indium, tin, and lead have yielded values for the heat of melting of sodium nitrate. Analysis of these results along with those from earlier investigations gives ΔHm − 3615 cal mol−1 as a recommended “best” value for the heat of melting of NaNO3. The consistency of our results over a period of three years in which many samples were investigated, in combination with results of earlier investigations, leads us to suggest that NaNO3 is a useful substance for calibration of differential scanning calorimeters. Results of our measurements of the heat of melting of indium are presented and discussed in relation to earlier investigations.

Heats of transition and melting of sodium nitrate by differential scanning calorimetry: use of indium and sodium nitrate as calibration substances

Abstract Information about the heat of melting of indium is summarized and a best value of the ΔHm is selected for use in calibrating differential scanning calorimeters. We have reviewed earlier determinations of the heat of melting of sodium nitrate and have made new measurements with a Perkin-Elmer DSC-2, all leading to a selected ΔHm that can also be used for subsequent calibration. Further DSC measurements have led to a ΔHtr for the solid—solid transition that occurs 31° below the melting point. Finally, we have established that “ordinary” care with sample handling is sufficient to avoid problems due to water pick-up by sodium nitrate.

Enthalpies of formation of lead chromate, lead molybdate, and lead tungstate, and the entropy of aqueous tungstate ion☆

Abstract We have made calorimetric measurements leading to δHfo = −927.02 kJ mol−1 for PbCrO4(c), δHfo = − 1052.66 kJ mol−1 for PbMoO4(c), and δHfo = − 1127.17 kJ mol−1 for PbWO4(c), all at 298.15 K. Various thermodynamic calculations are based on these results and others taken from earlier investigations.

Apparent molar heat capacities and volumes of silver nitrate and silver perchlorate in aqueous solution at 298 K

Abstract We have made calorimetric and density measurements leading to apparent molar heat capacities and volumes of dilute aqueous solutions of silver nitrate and silver perchlorate at 298 K. Resulting apparent molar properties at infinite dilution are the following: φ o c (AgNO 3 ) = − 36.8 J K −1 mol −1 , φ o v (AgNO 3 ) = 29.1 cm 3 mol −1 , φ o c (AgClO 4 ) = 11.0 J K −1 mol −1 , and φ o v (AgClO 4 ) = 43.5 cm 3 mol −1 .