Thermodynamics of acid dissociation of aqueous bisulfite ion: ΔH0, ΔCP0, and ΔV0 at 298.15 K

1981 ◽  
Vol 59 (7) ◽  
pp. 1068-1073 ◽  
Author(s):  
Gregory C. Allred ◽  
John W. Larson ◽  
Loren G. Hepler
Keyword(s):  
Pressure Dependence ◽  
Acid Dissociation ◽  
Dissociation Reaction ◽  
Density Measurements ◽  
Carbonate Ion ◽  
Calorimetric Measurements ◽  
Enthalpy Of Proton Transfer ◽  
Temperature And Pressure ◽  
Enthalpy Of Protonation ◽  
Sulfite Ion

Calorimetric measurements of the enthalpy of protonation of sulfite ion and the enthalpy of proton transfer from bisulfite ion to carbonate ion have led to two independent values for the standard enthalpy of the acid dissociation reaction represented by HSO3−(aq) = H+(aq) + SO32− (aq). Further calorimetric and density measurements have led to apparent and partial molar heat capacities and volumes for sulfite and bisulfite ions. Results of all of these measurements are summarized by ΔH0 = −3.59 ± 0.10 kJ mol−1, ΔCP0 = −262 ± 7 J K−1 mol−1, and ΔV0 = −28.7 ± 1.0cm3 mol−1 for the acid dissociation of HSO3− (aq) at 298.15 K. These results are used for thermodynamic calculations of the temperature and pressure dependence of the equilibrium constant for acid dissociation of HSO3− (aq).

Heat capacities and volumes of dissociation of phosphoric acid (1st, 2nd, and 3rd), bicarbonate ion, and bisulfate ion in aqueous solution

1982 ◽  
Vol 60 (16) ◽  
pp. 2141-2150 ◽  
Author(s):  
John W. Larson ◽  
Kevin G. Zeeb ◽  
Loren G. Hepler
Keyword(s):  
Text Analysis ◽  
Heat Capacities ◽  
Acid Dissociation ◽  
Apparent Molar Heat Capacities ◽  
Flow Calorimeter ◽  
Buffer Solutions ◽  
Calorimetric Measurements ◽  
State Formula ◽  
Effects Of Temperature ◽  
Temperature And Pressure

Measurements at 25 °C with a flow calorimeter and a flow densimeter have led to heat capacities and densities of aqueous solutions of H3PO4, NaH2PO4, Na2HPO4, Na3PO, NaHCO3, Na2CO3, H2SO4, and various buffer solutions. Results are presented in terms of apparent molar heat capacities [Formula: see text] and apparent molar volumes [Formula: see text]. Analysis of the experimental [Formula: see text] values to obtain the desired standard state [Formula: see text] values for single electrolytes requires that allowance be made for hydrolysis and dissociation reactions of certain solutes, along with extrapolation to zero concentration. Analysis of [Formula: see text] values requires similar considerations of hydrolysis and dissociation reactions, allowance for enthalpy and equilibrium changes ("relaxation") during calorimetric measurements, and extrapolation to zero concentration. Procedures for these calculations are presented. The [Formula: see text] and [Formula: see text] values that result from all of these measurements and calculations are used to obtain ΔCp0 and ΔV0 values for acid dissociation reactions, which are then related to effects of temperature and pressure on other thermodynamic properties.

Measurements of real non-Newtonian response for liquid lubricants under moderate pressures

2001 ◽  
Vol 215 (3) ◽  
pp. 223-233 ◽  
Author(s):  
S Bair
Keyword(s):  
Numerical Simulation ◽  
Kinetic Theory ◽  
Simple Shear ◽  
Pressure Dependence ◽  
Shear Stresses ◽  
Current Interest ◽  
Flow Properties ◽  
Power Law Fluid ◽  
Temperature And Pressure

A thorough characterization of all viscous flow properties relevant to steady simple shear was carried out for five liquid lubricants of current interest to tribology. Shear stresses were generated to values significant to concentrated contact lubrication. Two types of non-Newtonian response were observed: shear-thinning as a power-law fluid and near rate-independence. Functions and parameters were obtained for the temperature and pressure dependence of the viscosity and of the time constant for the Carreau-Yasuda equation. Results are consistent with free volume and kinetic theory, but directly contradict many assumptions currently utilized for numerical simulation and for extracting rheological properties from contact measurements.

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

On the temperature and pressure dependence of dielectric relaxation processes in ionic liquids

2021 ◽  
Author(s):  
Florian Pabst ◽  
Zaneta Wojnarowska ◽  
Marian Paluch ◽  
Thomas Blochowicz
Keyword(s):  
Ionic Liquids ◽  
Dielectric Relaxation ◽  
Pressure Dependence ◽  
Dynamic Processes ◽  
Relaxation Processes ◽  
Dielectric Spectra ◽  
Temperature And Pressure ◽  
Microscopic Origin

The temperature and pressure dependence of two dynamic processes in the dielectric spectra of five supercooled ionic liquids equipped with octyl-chains are reported. The microscopic origin of these processes is discussed.

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