THE ENTROPIES OF IONS IN AQUEOUS SOLUTION: II. AN EMPIRICAL EQUATION FOR OXY-ANIONS

1957 ◽  
Vol 35 (3) ◽  
pp. 202-206 ◽  
Author(s):  
A. M. Couture ◽  
K. J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Interatomic Distance ◽  
Empirical Equation ◽  
Central Atom ◽  
Van Der Waals ◽  
Empirical Relationship ◽  
Mean Deviation ◽  
A Value

The entropies of oxy-anions in aqueous solution are shown to obey the empirical relationship[Formula: see text]with a mean deviation of 3.6 e.u. In this equation [Formula: see text] is the entropy relative to a value of −5.5 e.u. for the proton, M is the molecular weight, z the number of charges on the ion, n the number of charge-bearing ligands, r is equal to r12 + 1.40, where r12 is the interatomic distance between the central atom and the surrounding oxygens, and 1.40 is the van der Waals radius of oxygen. The significance of the empirical equation is discussed.

Dependence of the Second Virial Coefficient of Aqueous Solutions of Small Non-Electrolytes on Partial Molar Volume and Molecular Weight of the Solutes

1993 ◽  
Vol 46 (6) ◽  
pp. 929 ◽  
Author(s):  
K Kiyosawa
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Aqueous Solutions ◽  
Molar Volume ◽  
Partial Molar Volume ◽  
Virial Coefficient ◽  
Van Der Waals ◽  
Second Virial Coefficient ◽  
Aqueous Systems ◽  
Quadratic Equations

The osmotic pressures of aqueous solutions of small non-electrolytes, namely ethane-1,2-diol, propane-1,2,3-triol, sucrose and raffinose , were found to be expressible by quadratic equations of the molar concentration, which indicate that these aqueous systems involve no term higher than the second virial coefficient A2. Analysis has shown that A2 mainly does not arise from non-ideality of the aqueous solutions, but its magnitude depends on the partial molar volume of the solute, more precisely on the molecular weight or van der Waals radius or volume of the solute in the aqueous solution.

THE PARTIAL MOLAL VOLUMES OF IONS IN AQUEOUS SOLUTION: II. AN EMPIRICAL EQUATION FOR OXY-ANIONS

1957 ◽  
Vol 35 (3) ◽  
pp. 207-210 ◽  
Author(s):  
A. M. Couture ◽  
K. J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Empirical Equation ◽  
Preceding Paper ◽  
Effective Radius ◽  
Density Data ◽  
A Value ◽  
Partial Molal Volumes ◽  
Molal Volumes ◽  
The One

The partial molal volumes of oxy-anions, obtained from density data, have been correlated with the radius, the charge, and the number of ligands of the ions. The volumes relative to a value of −6.0 ml. for the proton are represented by the equation:[Formula: see text]where r and z_ have the same significance as in the preceding paper on entropies. The equation is compared with the one for monatomic ions, and the significance of the effective radius r is discussed.

scholarly journals Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1218
Author(s):  
Raffael Rathner ◽  
Wolfgang Roland ◽  
Hanny Albrecht ◽  
Franz Ruemer ◽  
Jürgen Miethlinger
Keyword(s):  
Molecular Weight ◽  
Pressure Drop ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Parallel Plate ◽  
Empirical Relationship ◽  
Polymer Processing ◽  
High Density ◽  
Viscosity Data ◽  
Molecular Masses

The Cox-Merz rule is an empirical relationship that is commonly used in science and industry to determine shear viscosity on the basis of an oscillatory rheometry test. However, it does not apply to all polymer melts. Rheological data are of major importance in the design and dimensioning of polymer-processing equipment. In this work, we investigated whether the Cox-Merz rule is suitable for determining the shear-rate-dependent viscosity of several commercially available high-density polyethylene (HDPE) pipe grades with various molecular masses. We compared the results of parallel-plate oscillatory shear rheometry using the Cox-Merz empirical relation with those of high-pressure capillary and extrusion rheometry. To assess the validity of these techniques, we used the shear viscosities obtained by these methods to numerically simulate the pressure drop of a pipe head and compared the results to experimental measurements. We found that, for the HDPE grades tested, the viscosity data based on capillary pressure flow of the high molecular weight HDPE describes the pressure drop inside the pipe head significantly better than do data based on parallel-plate rheometry applying the Cox-Merz rule. For the lower molecular weight HDPE, both measurement techniques are in good accordance. Hence, we conclude that, while the Cox-Merz relationship is applicable to lower-molecular HDPE grades, it does not apply to certain HDPE grades with high molecular weight.

scholarly journals MYOHEMOGLOBINURIA

1941 ◽  
Vol 74 (3) ◽  
pp. 187-196 ◽  
Author(s):  
Charles L. Yuile ◽  
William F. Clark
Keyword(s):  
Molecular Weight ◽  
Plasma Concentration ◽  
Creatinine Clearance ◽  
Glomerular Filtration ◽  
Renal Clearance ◽  
Renal Excretion ◽  
Clearance Ratio ◽  
A Value ◽  
Blood Hemoglobin

When myohemoglobin is injected intravenously into dogs, in amounts ranging from 0.75 to 1.50 gm., it is rapidly eliminated from the plasma and approximately 65 per cent is excreted by the kidneys in from 1½ to 2½ hours. Myohemoglobin does not appear in the urine below a threshold plasma concentration which is slightly under 20 mg. per 100 cc. but above this level the rate of renal excretion is directly proportional to the plasma concentration. The maximum myohemoglobin/creatinine clearance ratio averages 0.58 contrasted with a value of 0.023 for blood hemoglobin. This indicates that the rate of renal clearance of myohemoglobin is twenty-five times more rapid than that of blood hemoglobin. Evidence is presented that the excretory mechanism is essentially similar for the two substances but that differences in molecular weight account for different rates of glomerular filtration.

scholarly journals THE MOLECULAR WEIGHT OF RHODOPSIN AND THE NATURE OF THE RHODOPSIN-DIGITONIN COMPLEX

1954 ◽  
Vol 37 (3) ◽  
pp. 381-399 ◽  
Author(s):  
Ruth Hubbard
Keyword(s):  
Molecular Weight ◽  
Single Molecule ◽  
Extinction Coefficient ◽  
Dry Weight ◽  
Weight Basis ◽  
Sedimentation Behavior ◽  
A Value ◽  
Wet Weight ◽  
Single Boundary ◽  
Stoichiometric Complex

The sedimentation behavior of aqueous solutions of digitonin and of cattle rhodopsin in digitonin has been examined in the ultracentrifuge. In confirmation of earlier work, digitonin was found to sediment as a micelle (D-1) with an s20 of about 6.35 Svedberg units, and containing at least 60 molecules. The rhodopsin solutions sediment as a stoichiometric complex of rhodopsin with digitonin (RD-1) with an s20 of about 9.77 Svedberg units. The s20 of the RD-1 micelle is constant between pH 6.3 and 9.6, and in the presence of excess digitonin. RD-1 travels as a single boundary also in the electrophoresis apparatus at pH 8.5, and on filter paper at pH 8.0. The molecular weight of the RD-1 micelle lies between 260,000 and 290,000. Of this, only about 40,000 gm. are due to rhodopsin; the rest is digitonin (180 to 200 moles). Comparison of the relative concentrations of RD-1 and retinene in solutions of rhodopsin-digitonin shows that RD-1 contains only one retinene equivalent. It can therefore contain only one molecule of rhodopsin with a molecular weight of about 40,000. Cattle rhodopsin therefore contains only one chromophore consisting of a single molecule of retinene. It is likely that frog rhodopsin has a similar molecular weight and also contains only one chromophore per molecule. The molar extinction coefficient of rhodopsin is therefore identical with the extinction coefficient per mole of retinene (40,600 cm.2 per mole) and the E(1 per cent, 1 cm., 500 mµ) has a value of about 10. Rhodopsin constitutes about 14 per cent of the dry weight, and 3.7 per cent of the wet weight of cattle outer limbs. This corresponds to about 4.2 x 106 molecules of rhodopsin per outer limb. The rhodopsin content of frog outer limbs is considerably higher: about 35 per cent of the dry weight, and 10 per cent of the wet weight, corresponding to about 2.1 x 109 molecules per outer limb. Thus the frog outer limb contains about five hundred times as much rhodopsin as the cattle outer limb. But the relative volumes of these structures are such that the ratio of concentrations is only about 2.5 to 1 on a weight basis. Rhodopsin accounts for at least one-fifth of the total protein of the cattle outer limb; for the frog, this value must be higher. The extinction (K500) along its axis is about 0.037 cm.2 for the cattle outer limb, and about 0.50 cm.2 for the frog outer limb.

scholarly journals Purification of acrylamide from polymerization inhibitors in the manufacture of high quality flocculants based on polyacrylamide

2020 ◽  
Vol 3 (2) ◽  
pp. 109-113
Author(s):  
V. P. Duleba ◽  
◽  
Z. Ya. Hnativ ◽  
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Polymerization Process ◽  
Iron Ions ◽  
Laboratory Studies ◽  
Catalytic Method ◽  
High Quality ◽  
Variable Valence ◽  
Sulfuric Acid Method ◽  
Practical Information

Polyacrylamide and its copolymers are widely used as flocculating agents for the separation of industrial suspensions. The formation of high molecular weight polymers depends on the content of various impurities present in the monomer. The article presents the scientific and practical information on the production of acrylamide by sulfuric acid method of hydration of nitrile acrylic acid in the form of an aqueous solution of different concentrations and a more modern heterogeneously catalytic method of hydration of acrylonitrile using as catalysts with variable valence. Ways to get different impurities in the stages of production of acrylamide with the purpose of applying appropriate methods for its purification. Laboratory studies of the purification of an aqueous solution of acrylamide from iron ions were carried out as an element of inhibition of the premature polymerization process.

Complexation of arsenate to humic acid with different molecular weight fractions in aqueous solution

2021 ◽  
pp. 1-7
Author(s):  
Shifeng Li ◽  
Feng Lu ◽  
Hongtao Lv ◽  
Yang Zhou ◽  
Mario A. Gomez ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Humic Acid ◽  
Molecular Weight Fractions ◽  
Different Molecular Weight

scholarly journals Low Molecular Weight Gelators Based on Functionalized l-Dopa Promote Organogels Formation

Gels ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 27 ◽  
Author(s):  
Demetra Giuri ◽  
Nicola Zanna ◽  
Claudia Tomasini
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Rheological Properties ◽  
Rhodamine B ◽  
Lauric Acid ◽  
Water Solution ◽  
Preliminary Test ◽  
Low Molecular Weight ◽  
Coupling Reactions ◽  
Low Molecular Weight Gelators

We prepared the small pseudopeptide Lau-l-Dopa(OBn)2-d-Oxd-OBn (Lau = lauric acid; l-Dopa = l-3,4-dihydroxyphenylalanine; d-Oxd = (4R,5S)-4-methyl-5-carboxyl-oxazolidin-2-one; Bn = benzyl) through a number of coupling reactions between lauric acid, protected l-Dopa and d-Oxd with an excellent overall yield. The ability of the product to form supramolecular organogels has been tested with different organic solvents of increasing polarity and compared with the results obtained with the small pseudopeptide Fmoc-l-Dopa(OBn)2-d-Oxd-OBn. The mechanical and rheological properties of the organogels demonstrated solvent-dependent properties, with a storage modulus of 82 kPa for the ethanol organogel. Finally, to have a preliminary test of the organogels’ ability to adsorb pollutants, we treated a sample of the ethanol organogel with an aqueous solution of Rhodamine B (RhB) for 24 h. The water solution slowly lost its pink color, which became trapped in the organogel.

scholarly journals Structure of stretched rubber.

1938 ◽  
Vol 164 (919) ◽  
pp. 491-496 ◽  
Author(s):  
C. J. Birkett Clews ◽  
F. Schoszberger ◽  
William Lawrence Bragg
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Pictorial Representation ◽  
Alternative Theory ◽  
Crystalline Region ◽  
Double Refraction ◽  
Micellar Structure ◽  
X Ray

Investigations of the micellar structure of fibre substances have given rise to two theories. The older theory (Meyer and Mark 1930; Mark 1932; Siefriz 1934; Meyer 1930; and Nageli 1928) considers the micelles as separate crystallites, between which lie the intermicellar spaces. The micelles consist of “Hauptvalenzketten” bound together along their length by homeopolar bonds and in the transverse direction by van der Waals’ forces, the intermicellar binding being also attributed to van der Waals’ forces. The original model suggested in work published by K. H. Meyer (1930), for cellulose, depicts the micelles arranged like bricks in a wall (fig. 1), and doubtless this is the simplest explanation of the X-ray results. But it is difficult to understand how such an arrangement can give a micellar structure its peculiar mechanical properties, and further how it is possible, when both inter- and intramicellar cohesion are attributed to the same type of force, to cause by swelling experiments an enlargement of the intermicellar spaces, while the “Hauptvalenzketten” remain unaffected. An alternative theory has been put forward by O. Gerngross, K. Herrmann and W. Abitz (1930), W. T. Astbury (1933), A. Frey-Wyssling (1936) and E. Guth and S. Rogowin (1936). These authors suppose that a given “Hauptvalenzkette” is not confined to a single crystalline region but may stretch through more such regions. In general, the arrangement of the neighbouring chains will be truly lattice-like, but a chain may lie at too great a distance from its neighbours or not lie exactly parallel to them, so that the structure as a whole will show statistically distributed spaces. In fig. 2 ordered crystalline regions may be distinguished (drawn in thick line), but their significance is physically different from that of the crystallites of the Meyer model. They are not self-contained units; the whole system is linked together due to the “Hauptvalenzketten” extending beyond a single micelle. Astbury considers that in a substance of high molecular weight of a type capable of swelling that part which produces the X-ray spectrum is the concentration centre of a complicated network of thread-like molecules. He draws an analogy between micellar structure and the secondary structure of Zwicky. He suggests that it is possible that micellar systems, which are characterized by a mixture of perfection and imperfection, are the counterpart in compounds of high molecular weight of the well-known mosaic structure of the more familiar crystals. Frey-Wyssling is of the opinion that the micelles, growing together, enclose lens-shaped spaces running parallel to the fibre axis. Between these intermicellar spaces are small rod-shaped regions of undistorted lattice, which are the so-called micelles of the earlier work (fig. 3). In this figure, which gives a pictorial representation of Frey’s theory, the statistically distributed hollow spaces are shown black; some of these are enclosed in undistorted crystalline regions. A lamellar structure consisting of superimposed monomolecular layers suggested by O. L. Sponsler and W. H. Dore (1930) has been shown to be untenable from the work on double refraction by Baas-Becking and Galliher (1931).

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