Slopes of pv isotherms of He, Ne, A, H2, N2, and O2 at 0 degrees C

To satisfy the de mand for data on oxygen at higher pressures, an equation has been developed that represents the available experimental data wit hin t he acc uracy of the observed val ues. Values of t he vi d al coefficients are given for densities in Amagat units in the temperature range -200° to + 200° C. Val uefl of pressure in po unds per square inch 2 are tabulated co rrespondin g to tem peratures from -50° to + 150° F and den~itie s up to 320 times the density at 70° F and 1 atmos phere. These data are also presented in a char t , wit;h pVj RT and pressure as coordinates. I. Equation of StateThe use of progressively high er pressures in , high-pressure containers has developed a need for data on oxygen at pressures and densities higher than those at present tabulated. Although a n equa tion for r epresenting the proper ties of oxygen has been publish ed by M illar and Sullivan [ to add tcrms con taining higher powers of V for making the cquation applicable at higher densities. No attempt h a b een made to see wheth er the form of temperature function used hcr e could be extend ed to such additional terms.A study of ch arts of p V versu l /V for several substances shows that a lincar r elation exists b etween the minimum values of p V for the various isotherms and their corresponding values of density. If this linear r elation may be extrapolated to low temperatures where the minimum occurs in the region of the subcooled liquid and cannot be r eproduced experimentally , th en since the density of the condensed phase is fini te, the minimum value of p V should also be finite, even though negative at the lower temper atures. The form of temperature functions used in eq 1 h ave b een designed such th at th eir product with T rema ins finite as T approaches zero ; and in this respect are considered to b e better than those used for butadiene [2J , although the constants for th e second virial can b e chosen so that over a wide temperature range the two functions will give values v ery closely in agr eem ent. The form BI /T4 + B z, which was used for the third viTial in the equation for butadien e, b ecomes at high .temperatures a close approx imation to the form used h ere.The valu e of M was determined by a m ethod of successive approximations. The procedure consisted in assuming a value for ]'111, solving-for B1 and B2 from valu es of th e second v irial deri ved from th e experimen tal data at two temper ature's, 457

Section: Journal Of Researchsupporting

confidence: 78%

Pressure-volume-temperature data for oxygen

Meyers¹

1948

“…(9) ' When mOR is known, the ionic strength may also be calculated: (10) Th e molality of hydroxyl ion, mOR, can be computed directly from the emf data by the equation…”

Section: Discussion Of the Ele Ctromotive-force Meth Odmentioning

confidence: 99%

“…determined electrometrically. Indicates that a 0.04-M solution of disodlum phenolate sulfonate has a pH of about 10 Anhydrous potassium p-phenolsulfonate is the form of the salt stable at room temperature. When exposed to laboratory air of about 20-to 30-percent humidity, a dry sample absorbed 0.03 to 0.05 percent of moisture.…”

Section: Methodsmentioning

confidence: 99%

“…Phenolsulfonate solutions are most satisfactory as pH standards when the molality of each constituent of the buffer is between 0.01 and 0.05. With the use of eq 13, the pH values of a phenolsulfonate buffer in which the molalities of the phenolsulfonate, phenolate sulfonate, and chloride ions are each 0.025 have been computed and are given in table 10. This solution is prepared most conveniently by dissolving 0.05 mole (10 .613 g) of potassium p -phenolsulfonate and 0.025 mole (1.461 g) of sodium chloride in sufficient carbonate-free sodium hydroxide solution to contain 0.025 mole of alkali.…”

Section: _09744mentioning

confidence: 99%

See 1 more Smart Citation

The second dissociation constant of p-phenolsulfonic acid and pH values of phenolsulfonate-chloride buffers from 0 degrees to 60 degrees C

Bates¹,

Siegel²,

Acree³

1943

The thermodynamic dissociation constant of the phenol group of p-phenolsulfonic acid was calculated from electromotive-force measurements of hydrogensilver-chloride cells without liquid junction. Thirty-nine buffer mixtures of potassium p-phenolsulfonate, sodium hydroxide, and sodium chloride were studied in five series of experiment s from 0° to 60° C at intervals of 5 degrees. In three series, t he molal ratio of phenolsulfonate ion to phenolate-sulfonate ion was unity, and in two series the buffer ratio was 2 :3. For two series of experiments, one at each buffer ratio, the molality of sodium chloride was m aintained constant near 0.05 for all dilutions of t he buffer. In the other experiments, the molality of each component of t he solut ion varied bet ween 0.0037 and 0.1.The values of pK2' the negative of the common logarithm of the second dissociat ion constant, between 0° and 60° C are given by the equation012139T, where T is in degrees Kelvin.Equations were formulated to give the changes of free energy, heat content, entropy, and heat capacity that accompany t he dissociation, at infinite dilution, of a mole of phenolsulfonate ion at any temperature between 0° and 60° C. For the dissociation of the phenol group at 25° C, ~F o is 12,351 cal, ~Ho is 4,036 cal, ~So is -27.9 cal deg-1, and ~c o p is -33 cal deg-1•The pH value of each buffer-chloride mixture was calculated from the experimental data and the activity coefficients that were found to characterize each series of solutions. The pH values of other phenolsulfonate buffers which have m olal ratios, mdm2, of phenolsulfonate ion to bivalent phenolate-sulfonate ion between 2/3 and 1 can be computed for temperatures between 0° and 60° C with an accuracy of ± 0.002 unit from their compositions and from the dissociation constants and ionic parameters given in this paper. The equation used is pH =pK2 -log (mt/m2) -3A.JJ;f(1 +8B-V JL), where JL is the ionic strength . Buffer solutions of this type are suitable pH standards in the range 8.6 to 9.0. CONTENTS

“…-logii=l +B a r/M -(3J.l, (3) where p. is the ionic strength (%~mizD, Zi is the valence of the ion, the molality of which is mi, and A and B are constants that vary only with the temperature and dielectric constant of the solution. The values of A and B at 20°, 25°, and 30° C [6] are given in table 1, together with EO and k.…”

Section: Azij-;;'mentioning

confidence: 99%

Dissociation constants and pH-titration curves at constant ionic strength from electrometric titrations in cells without liquid junction: titrations of formic acid and acetic acid

Bates¹,

Siegel²,

Acree³

1943

An improved method for obtaining the titration curves of monobasic acids is outlined. The sample, 0.005 mole of the sodium salt of the weak acid, is dissolver! in 100 ml of a 0.05-m solution of sodium chloride and titrated electrometrically with an acid-salt mixture in a hydrogen-silver-chloride cell without liquid junction.The acid-salt mixture has the composition: nitric acid, 0.1 m; pot assium nitrate, 0.05 m; sodium chloride, 0.05 m. The titration therefor e is performed in a. medium of constant chloride concentration and of practically unchanging ionicstr ength (1'=0.1) . The calculations of pH values and of dissociation constants from the emf values are outlined . The tit ration curves and dissociation constants of form ic acid and of acetic acid at 25 0 C were obtained by this method. The pK values (negative logarit hms of the d issociation constants) were found to be 3.742 and 4. 754, respectively.