pH values of certain phosphate-chloride mixtures, and the second dissociation constant of phosphoric acid from 0 degrees to 60 degrees C

Bates, Roger G.; Acree, S. F.

doi:10.6028/jres.030.012

Cited by 186 publications

(91 citation statements)

References 24 publications

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“…We suggest that our ACpO = -220 J K-' mol-I is the best available value. Although we are generally skeptical of ACpO values based on double differentiation of log K = f(T), we note that the equilibrium constants of Bates and Acree (26) and Grzybowski (28) appear to have been determined with considerable skill and accuracy; it is therefore gratifying to note that their (26,28) ACpO values are in good agreement with our value.…”

Section: Comparisons Of Resultssupporting

confidence: 73%

“…For the third dissociation we select the K value from Quist and Vanderzee (38). Enthalpies for these dissociations have been selected from values calculated with dln K/dT = AH0/RT2 (23,24,(26)(27)(28) and from results of calorimetric measurements (39)(40)(41)(42)(43). The selected ACpO values are all based on our calorimetric results as reported in this paper.…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

“…Equilibrium constants for the first and second dissociations of phosphoric acid have already been cited (23)(24)(25)(26)(27)(28). For the third dissociation we select the K value from Quist and Vanderzee (38).…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

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

Larson¹,

Zeeb²,

Hepler³

1982

Can. J. Chem.

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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.

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Section: Comparisons Of Resultssupporting

confidence: 73%

Section: Thermodynamic Calculationsmentioning

confidence: 99%

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

Larson¹,

Zeeb²,

Hepler³

1982

Can. J. Chem.

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“…No cytological signs of strong shortening in terms of Cz and C m bands were seen in fibrils from 5 The refractive index of nitrobenzene is intermediate to the refractive indices of acetone-dehydrated Drosophila muscle fibrils. When one observes a fibril with green polarized light at 25°C by phase-contrast microscopy, it is possible to see images which are matched, overmatched, or undermatched, depending on the plane of polarization.…”

Section: In Vivo Comparisonmentioning

confidence: 99%

“…The pH of all solutions was determined at room temperature and this value was used as the nominal pH at other temperatures. The effect of temperature on the phosphate buffer generally used was not studied, but the work of Bates and Acree (5) indicates that the change in pH between 24 ° and 60°C will be small at pH 7. W h e n a Drosophila fibril was heated, a characteristic sequence of changes was visible by phasecontrast microscopy.…”

Section: Methodsmentioning

confidence: 99%

A Melting Point for the Birefringent Component of Muscle

Aronson

1966

The Journal of Cell Biology

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The A filament of the striated muscle sarcomere is an ordered aggregate of one or a few species of proteins. Ordering of these filaments into a parallel array is the basis of birefringence in the A region, and loss of birefringence is therefore a measure of decreased order. Heating caused a large decrease in the birefringence of glycerinated rabbit psoas muscle fibers over a narrow temperature range (∼3°C) and a large decrease in both the birefringence and optical density of the A region of Drosophila melanogaster fibrils. These changes were interpreted as a loss of A filament structure and were used to define a transition temperature (Ttr) as a measure of the stability of the A region. Since the transition temperature was sensitive to pH, ionic strength, and urea, solvent conditions which often affect protein structure, it is an experimentally useful indicator for factors affecting the structure of the A filament. Fibers from glycerinated frog muscle were less stable over a wide pH range than fibers from glycerinated rabbit muscle, a fact which demonstrates a species difference in structure. Glycerinated rabbit fibrils heated to 70°C shortened to about 40% of their initial length. The extent of shortening was not correlated with the loss of birefringence, and phase-contrast microscopy showed that this shortening occurred in the I region as well as in the A region. This response may be useful for studying the I filament and actin in much the same way that the decrease in birefringence was used for studying the A filament and myosin. The observations presented show that some properties of muscle proteins can be studied essentially in situ without the necessity of first dispersing the structure in solutions of high or low ionic strength.

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Solubility product of OH-carbonated hydroxyapatite

Ito¹,

Maekawa

Tsutsumi

et al. 1997

J. Biomed. Mater. Res.

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Information on the solubility of OH-carbonated hydroxyapatite, Ca10(PO4)6(CO3)x(OH)2-2x, previously has not been available. In the present study the solubility product (Ksp) of OH-carbonated hydroxyapatite was measured in a 0.1 M acetic acid and sodium acetate buffer solution in a pH range of 4.0-5.8 at a CO2 partial pressure of 10(-3.52) atm. The equilibrium solubility increased with the increase of carbonate content. The Ksp values decreased with the decrease of pH. For example, Ksps were 10(-119), 10(-123), and 10(-130) for pure hydroxyapatite at pH 4.9, 4.5, and 4.1, respectively. The decrease of Ksp was not accounted for by calcium-carbonate complexation. Ksp measured at isoelectric points (L) was expressed as pL = 118.65 - 0.47316 x (CO2 wt%)2.4176. From this formula, the L values were calculated for pure and fully carbonated hydroxyapatite as 10(-118.7) and 10(102.8), respectively. The L value for pure hydroxyapatite agreed with values measured under carbonate-free conditions. Therefore, the L values were regarded as the Ksp for OH-carbonated hydroxyapatite excluding errors arising from carbonate contamination in the solution.

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pH values of certain phosphate-chloride mixtures, and the second dissociation constant of phosphoric acid from 0 degrees to 60 degrees C

Cited by 186 publications

References 24 publications

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

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

A Melting Point for the Birefringent Component of Muscle

Solubility product of OH-carbonated hydroxyapatite

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