ISSN:
1572-8927
Keywords:
Heat capacities
;
flow calorimetry
;
densities
;
partial molar heat capacities
;
alkali metal ions
;
halide ions
;
tetraphenylphosphonium ion
;
tetraphenylborate ion
;
single ion values
;
methanol
;
dimethylsulfoxide
;
Debye-Hückel limiting law slopes
;
electrostriction and charge effect
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A high temperature-high pressure flow heat capacity calorimeter, designed to operate to 350°C and 20 Mpa, has been constructed and tested with aqueous sodium chloride solutions to 80°C. The calorimeter has been used to measure the specific heats for solutions of NaBr, NaClO4, φ4PBR, NaBφ4, and benzene in methanol (MeOH) and dimethylsulfoxide (DMSO) at 40 and 80°C. A commercial calorimeter was used to measure the same systems at 25°C. Apparent molar heat capacities C〉p,ϕ have been evaluated and extrapolated to infinite dilution to obtain standard partial molar heat capacities $$\bar C_{p,2}^{\text{o}} $$ . For electrolytes $$\bar C_{p,2}^{\text{o}} $$ are positive and insensitive to temperature to 80°C in DMSO, but in MeOH, C p, 2 0 for simple electrolytes are negative and become increasingly negative with temperature. The behavior in MeOH is attributed to strong electrostriction by ionic charge and solvation of anions by MeOH molecules which increases with temperature. This is similar to observed behavior of electrolytes in water above 100°C. For benzene $$\bar C_{p,2}^{\text{o}} $$ is positive in MeOH and DMSO, and increases with temperature.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00650993
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