Apparent molal heat capacities and volumes of aqueous hydrogen sulfide and sodium hydrogen sulfide near 25 °C: the temperature dependence of H2S ionization

A flow microcalorimeter and vibrating tube densimeter were used to obtain apparent molal heat capacities and volumes of aqueous NaHS and Na2S from 0.1 to 1.0 mol kg−1 and of aqueous H2S from 0.03 to 0.08 mol kg−1 at 10, 25, and 40 °C. Standard state heat capacities and volumes for H2S and HS− were obtained by extrapolation to infinite dilution. Combining these results with 25 °C enthalpy data yields an expression for the temperature dependence of the equilibrium constant for H2S neutralization at pressures near those of steam saturation, H2S + OH− = HS− + H2O, log K1b = 19.84 + 930.8/T−2.800 In T, with an estimated uncertainty of ±0.47 at 300 °C. The heat capacity data for bulk aqueous Na2S suggest that the relative concentration of S2− at these molalities is small.

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Apparent molal heat capacities and volumes of aqueous electrolytes at 25 °C: NaClO3, NaClO4, NaNO3, NaBrO3, NaIO3, KClO3, KBrO3, KIO3, NH4NO3, NH4Cl, and NH4ClO4

Canadian Journal of Chemistry ◽

10.1139/v78-004 ◽

1978 ◽

Vol 56 (1) ◽

pp. 24-28 ◽

Cited By ~ 46

Author(s):

Alain Roux ◽

Goolam M. Musbally ◽

Gérald Perron ◽

Jacques E. Desnoyers ◽

Prem Paul Singh ◽

...

Keyword(s):

Aqueous Solutions ◽

Infinite Dilution ◽

Heat Capacities ◽

Aqueous Electrolytes ◽

Apparent Molal Volumes ◽

Hückel Theory ◽

Standard Values ◽

Molal Volumes ◽

Apparent Molal Heat Capacities

Measurements at 25 °C with flow calorimeters and densimeters have led to heat capacities and densities of aqueous solutions of 11 1:1 electrolytes: NaClO3, NaBrO3, NaIO3, NaNO3, NaClO4, NH4NO3, KClO3, KBrO3, KIO3, NH4Cl, and NH4ClO4. The first 6 salts were studied up to near saturation. We have used results of these measurements to obtain apparent molal heat capacities and apparent molal volumes of the various solutes. Extrapolation to infinite dilution on the basis of the Debye–Hückel theory bas led to [Formula: see text]and [Formula: see text] values for each solute. We have compared these standard values with results of earlier investigations.

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Thermodynamics of aqueous carbon dioxide and sulfur dioxide: heat capacities, volumes, and the temperature dependence of ionization

Canadian Journal of Chemistry ◽

10.1139/v83-433 ◽

1983 ◽

Vol 61 (11) ◽

pp. 2509-2519 ◽

Cited By ~ 40

Author(s):

José A. Barbero ◽

Loren G. Hepler ◽

Keith G. McCurdy ◽

Peter R. Tremaine

Keyword(s):

Experimental Data ◽

Carbon Dioxide ◽

Infinite Dilution ◽

Heat Capacities ◽

Standard State ◽

Apparent Molar Heat Capacities ◽

Experimental Heat ◽

Chemical Relaxation ◽

Vibrating Tube Densimeter ◽

New Equation

A flow microcalorimeter and vibrating tube densimeter were used at 25 °C to obtain apparent molar heat capacities and volumes of aqueous NaHCO3, KHCO3, NaHSO3, and KHSO3, from 0.1 to 1.0 mol kg−1, aqueous CO2 from 0.01 to 0.10 mol kg−1 and aqueous SO2 from 0.045 to 2.0 mol kg−1. The contribution of "chemical relaxation" (changes in equilibrium state and enthalpy due to change in temperature) to the experimental heat capacities of aqueous SO2 required special attention, leading to the derivation of a new equation for calculating this effect. Standard state values for the heat capacities and volumes of aqueous CO2, SO2, HCO3−, and HSO3− were obtained from the apparent molar properties by extrapolation to infinite dilution. Combining these results with other thermodynamic data from the literature gave estimates of log K1b the equilibrium constant for the first neutralization of CO2 and SO2, at high temperatures. The results for CO2 reproduce very accurate literature values to within 0.2 at 200 °C. The expression for the reaction [Formula: see text] log K1b = 22.771 + 2776.0/T–8.058 log T, is consistent with the sparse and limited experimental data.

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Polyol–Water interactions. Apparent molal heat capacities and volumes of aqueous polyol solutions

Canadian Journal of Chemistry ◽

10.1139/v77-540 ◽

1977 ◽

Vol 55 (22) ◽

pp. 3825-3830 ◽

Cited By ~ 45

Author(s):

Giuseppa DiPaola ◽

Bernard Belleau

Keyword(s):

Aqueous Solutions ◽

Infinite Dilution ◽

Pure Water ◽

Water Environment ◽

Heat Capacities ◽

Flow Microcalorimeter ◽

Specific Heats ◽

Structural Interactions ◽

Apparent Molal Heat Capacities

Volumetric specific heats (25 °C) and densities (24 °C) were measured with a flow microcalorimeter and flow densimeter for 12 polyols in water (0.05 to 2 m), and for NaCl and n-Bu4NBr in 1 m aqueous alditol solutions. The infinite dilution properties [Formula: see text] of the polyols show specificities in polyol−water interactions which are discussed in terms of the compatibility of the polyol stereochemistry and the existing water environment. The derived heat; capacities and volumes of transfer of hydrophobic and hydrophilic probes to aqueous solutions of homologous polyols suggest that structural interactions are reduced in these systems as compared to pure water.

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Heat capacities of aqueous electrolytes: eight 1:1 electrolytes and ΔCp0 for ionization of water at 298 K

Canadian Journal of Chemistry ◽

10.1139/v76-477 ◽

1976 ◽

Vol 54 (21) ◽

pp. 3315-3318 ◽

Cited By ~ 31

Author(s):

Prem Paul Singh ◽

Earl M. Woolley ◽

Keith G. McCurdy ◽

Loren G. Hepler

Keyword(s):

Aqueous Solutions ◽

Infinite Dilution ◽

Heat Capacities ◽

Aqueous Electrolytes ◽

Flow Calorimeter ◽

Apparent Molal Heat Capacities ◽

Ionization Of Water

We have made measurements with a flow calorimeter leading to apparent molal heat capacities of aqueous solutions of NaCl, HCl, KBr, KCl, KOH, NaBr, HBr, and NaOH at 298 K. Results have been used to derive apparent molal heat capacities of these electrolytes at infinite dilution and thence ΔCp0 = −215.2 ± 4 J K−1mol−1 for ionization of H2O(liq) at 298 K.

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Capacités calorifiques, volumes, expansibilités et compressibilités des solutions aqueuses concentrées de LiOH, NaOH et KOH

Canadian Journal of Chemistry ◽

10.1139/v84-144 ◽

1984 ◽

Vol 62 (5) ◽

pp. 878-885 ◽

Cited By ~ 30

Author(s):

Alain H. Roux ◽

Gérald Perron ◽

Jacques E. Desnoyers

Keyword(s):

Temperature Dependence ◽

Least Squares ◽

Partial Molar Volumes ◽

Heat Capacities ◽

Ultrasonic Velocities ◽

Hückel Theory ◽

Least Squares Fit ◽

Vibrating Tube Densimeter ◽

Alkali Hydroxides ◽

Partial Molar Compressibilities

The densities and heat capacities of various alkali hydroxides were measured in water with a vibrating tube densimeter and a flow microcalorimeter in the temperature range 4 to 55 °C. The concentration ranges investigated were respectively: 0.04 to 3.8 mol kg−1 for LiOH, 0.02 to 10.9 mol kg−1 for NaOH, and 0.02 to 15.5 mol kg−1 for KOH. The partial molar volumes [Formula: see text] and heat capacities [Formula: see text]were calculated from the least-squares fit of the apparent molar quantities [Formula: see text] as a function of molalities. From the temperature dependence of these functions the apparent molar expansibilities [Formula: see text] and [Formula: see text] were derived. The ultrasonic velocities were also measured for the dilute solutions of NaOH at 25 °C, and can be used to calculate the standard partial molar compressibilities and isochoric heat capacities. The present data were compared with literature values. The general trends as a function of concentration are similar to those of other 1:1 electrolytes even though the deviations from the Debye–Hückel theory are larger.

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