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

1984 ◽  
Vol 62 (5) ◽  
pp. 878-885 ◽  
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.

Thermodynamic properties of aqueous diethanolamine (DEA), N,N-dimethylethanolamine (DMEA), and their chloride salts: apparent molar heat capacities and volumes at temperatures from 283.15 to 328.15 K

2000 ◽  
Vol 78 (1) ◽  
pp. 151-165 ◽  
Author(s):  
Christopher Collins ◽  
Joelle Tobin ◽  
Dmitri Shvedov ◽  
Rom Palepu ◽  
Peter R Tremaine
Keyword(s):  
Partial Molar Volumes ◽  
Heat Capacities ◽  
Apparent Molar Heat Capacities ◽  
Molar Volumes ◽  
Partial Molar Heat Capacities ◽  
Relaxation Effects ◽  
Chemical Relaxation ◽  
Young's Rule ◽  
Vibrating Tube Densimeter ◽  
Chloride Salts

Apparent molar heat capacities Cp,ϕ and apparent molar volumes Vϕ for aqueous diethanolamine (HOC2H4)2NH, diethanolammonium chloride (HOC2H4)2NH2Cl, N,N'-dimethylethanolamine (HOC2H4)(CH3)2N, and N,N'-dimethylethanolammonium chloride (HOC2H4)(CH3)2NHCl were determined from 283.15 to 328.15 K with a Picker flow microcalorimeter and vibrating tube densimeter. The experimental results have been analyzed in terms of Young's Rule with the Guggenheim form of the extended Debye-Hückel equation and appropriate corrections for chemical relaxation effects. These calculations lead to standard partial molar heat capacities and volumes for the neutral amines, (HOC2H4)2NH(aq) and (HOC2H4)(CH3)2N(aq), and the ions (HOC2H4)2NH2+(aq) and (HOC2H4)(CH3)2NH+(aq) over the experimental temperature range. Key words: standard partial molar volumes, standard partial molar heat capacities, diethanolamine, dimethyethanolamine, aqueous alkanolamine ionization.

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

1982 ◽  
Vol 60 (14) ◽  
pp. 1872-1880 ◽  
Author(s):  
José A. Barbero ◽  
Keith G. McCurdy ◽  
Peter R. Tremaine
Keyword(s):  
Hydrogen Sulfide ◽  
Temperature Dependence ◽  
Infinite Dilution ◽  
Relative Concentration ◽  
Heat Capacities ◽  
Sodium Hydrogen ◽  
Vibrating Tube Densimeter ◽  
Capacity Data ◽  
Apparent Molal Heat Capacities ◽  
Enthalpy Data

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.

Changes in total body calcium balance with exercise in the rat

1983 ◽  
Vol 55 (1) ◽  
pp. 201-204 ◽  
Author(s):  
A. D. LeBlanc ◽  
H. J. Evans ◽  
P. C. Johnson ◽  
S. Jhingran
Keyword(s):  
Least Squares ◽  
Voluntary Exercise ◽  
Calcium Balance ◽  
Sprague Dawley ◽  
Total Body Calcium ◽  
Sprague Dawley Rats ◽  
Least Squares Fit ◽  
Significant Change ◽  
Total Body ◽  
And Control

The purpose of this study was to evaluate the effect of deconditioning on the total body calcium in rats. Two separate experiments were performed using female Sprague-Dawley rats, 187-266 days of age. Total body calcium was measured in experimental and control rats during and following several weeks of voluntary exercise. The slope from the least-squares fit of total body calcium with time was used to obtain an average calcium balance for each animal during each study period. In both groups the exercised rats had a significantly decreased calcium balance after cessation of exercise, whereas no significant change was seen in nonexercised controls. In both groups, the exercised animals gained calcium at a significantly greater rate than controls. Our findings indicate that while exercised rats may gain calcium at a faster rate compared with nonexercising controls, the rate of gain following cessation of exercise is less than the controls.

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