Partial molar heat capacities of selected electrolytes and benzene in methanol and dimethylsulfoxide at 25, 40, and 80/sup 0/C

Journal Article · Sun Nov 01 04:00:00 EST 1987 · J. Solution Chem.; (United States)

DOI:https://doi.org/10.1007/BF00650993· OSTI ID:6977758

Lankford, J I; Criss, C M

A high temperature-high pressure flow heat capacity calorimeter, designed to operate to 350/sup 0/C and 20 Mpa, has been constructed and tested with aqueous sodium chloride solutions to 80/sup 0/C. The calorimeter has been used to measure the specific heats for solutions of NaBr, NaClO/sub 4/, phi/sub 4/PBr, NaBphi/sub 4/, and benzene in methanol (MeOH) and dimethylsulfoxide (DMSO) at 40 and 80/sup 0/C. A commercial calorimeter was used to measure the same systems at 25/sup 0/C. Apparent molar heat capacities C > /sub p,phi/ have been evaluated and extrapolated to infinite dilution to obtain standard partial molar heat capacities C/sup 0//sub p,2/. For electrolytes C/sup 0//sub p,2/ are positive and insensitive to temperature to 80/sup 0/C in DMSO, but in MeOH, C/sup 0//sub p,2/ 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/sup 0/C. For benzene C/sup 0//sub p,2/ is positive in MeOH and DMSO, and increases with temperature.

• Research Organization: Univ. of Miami, Coral Gables, FL (USA)
• OSTI ID: 6977758
• Journal Information: J. Solution Chem.; (United States), Journal Name: J. Solution Chem.; (United States) Vol. 16:11; ISSN JSLCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
ALCOHOLS
ALKALI METAL COMPOUNDS
AROMATICS
BENZENE
BROMIDES
BROMINE COMPOUNDS
CALORIMETRY
CHARGE DISTRIBUTION
CHLORIDES
CHLORINE COMPOUNDS
DENSITY
DMSO
ELECTRIC CHARGES
ELECTROLYTES
ELECTROSTATICS
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
ION EXCHANGE
IONIZATION
MEDIUM TEMPERATURE
METHANOL
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PARTIAL MOLAL VOLUME
PERCHLORATES
PHOSPHORUS BROMIDES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
SODIUM BROMIDES
SODIUM CHLORIDES
SODIUM COMPOUNDS
SODIUM PERCHLORATES
SPECIFIC HEAT
SULFOXIDES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
VALENCE