Vapor Pressure Depression Research Articles

Copper(I) Perchlorate Complexes of Allyl, 2-Methylallyl and cis-and trans-2-Butenyl Alcohols

Abstract [Cu(allyl alcohol) (H2O)]ClO4 (abb. Cu(all)(H2O)ClO4), [Cu(allyl alcohol)2(H2O)]ClO4 (abb. Cu(all)2-(H2O)ClO4), [Cu(2-methylallylalcohol)(H2O)]ClO4 (abb. Cu(meth)(H2O)ClO4) and [Cu(cis- and trans-2-butenyl alcohol)2 (H2O)]ClO4 (abb. Cu(cis-and trans- but2 (H2O)ClO4) were synthesized. It was shown by means of equivalent conductance that Cu(all)(H2O)ClO4 is a strong electrolyte of uni-uni valent in acetone. The molecular weight of Cu(all)(H2O)ClO4 obtained from measurements of the direct vapor-pressure depression of acetone showed that the complex is monomeric. The C=C stretching band of the allylic alcohol shifts by about 100 cm−1 to the lower frequency side upon coordination. The chemical shifts of the vinyl protons in these complexes shift by about 0.5–1 ppm to the higher frequency side than those of free alcohols. It was concluded that the allylic alcohol coordinates to the copper atom through both the double bond and the oxygen atom. The equilibrium constant corresponding to Cu(trans-but)+2(H2O)ClO4+2cis-2-butenyl alcohol=Cu(cis-but)+2(H2O)ClO4+2trans-2-butenyl alcohol in 2-butenyl alcohol was estimated to be 9.82 at 25°C and the enthalpy change was estimated to be −3.13kcal/mol.

Micelle formation of oil-soluble surfactants in nonaqueous solutions: Effect of molecular structure of surfactants

The micellar weight of dialkylsulfosuccinates, dialkyldimethylammonium halides, and polyoxyethylene 2(1,3-dioctoxypropyl) ether in nonaqueous solutions was measured by the vapor pressure depression method. The apparent aggregation number of anionic surfactants approached saturation values above a fixed range of concentration, whereas that of cationic surfactants generally increased with increase of concentration. However, the nonionic surfactant formed no micelles in various solvents. The aggregation number (λ) of both anionic and cationic surfactants generally decreased with increase in the total carbon number of the alkyl group. The aggregation number of the anionic surfactant having the less bulky hydrocarbon group was larger than that of the anionic surfactant having the more bulky hydrocarbon group. The order of magnitude of λ of surfactants having hydrocarbon groups of equal size was anionics⪢ cationics > nonionics in various solvents. These results were compared with the results reported by other authors.

Light scattering and electrophoretic studies of mixed micelles of ionic and nonionic surfactants

Light scattering and electrophoretic studies have been made of the mixed micelles formed in the systems ofn-dodecyl nonaoxyethylene ether/sodium dodecyl sulfate (NaC12S), andi-octylphenyl nonaoxyethylene ether/NaC12S as a function of the mole ratio of nonionic/ionic surfactants. In the former system the micellar molecular weight increases simply with increasing nonionic content, while in the latter system it rises abruptly when the nonionic content exceeds about 50% by mole. This behaviour would be interpreted by a difference in hydrocarbon-chain attraction between these two systems. The degree of ionic dissociation, α, of NaC12S in the mixed micelles increases as the content of the nonionic surfactant increases. This tendency is in accordance with the previous result obtained by pNa and vapor pressure depression data. The value of α is closely related to the charge density, σ, on the surface of the micelle; α increasing with decreasing σ. The micellar charge for NaC12S alone, estimated from electrophoretic data, is much larger than that calculated from light scattering data by using the equation derived byMysels. For this discrepancy, a plausible explanation would be made by the different surfaces of the micelle measured by these two techniques.

Effect of salts and organic solvents on the activity of Halobacterium cutirubrum catalase.

Catalase in extracts of the extreme halophile Halobacterium cutirubrum exhibits up to threefold stimulation by 0.5 to 1.5 m monovalent salts and by 0.1 m divalent salts. Above these concentrations, inhibition of enzyme activity is observed. The inhibitory effect, and to some extent the stimulation, is salt-specific; the effectiveness of a salt in inhibiting enzyme activity depends on both cation and anion. Thus, the order of effectiveness is MgCl(2) > LiCl > NaCl > KCl > NH(4)Cl, and LiCl > LiNO(3) > Li(2)SO(4). The magnitude of enzyme inhibition for the salts tested is positively correlated with their molar vapor pressure depression in aqueous solution. Stimulation of enzyme activity was observed when one salt was added at its optimal concentration in the presence of inhibiting concentrations of another salt, indicating that the effect on the enzyme is not due to changing water activity but probably to enzyme-salt interaction. Aqueous solutions of ethylene glycol, glycerol, and dimethyl sulfoxide containing no ions influence enzyme activity in the same manner as do salts.

Some physical aspects of internal control of leaf transpiration

Although it is generally accepted that stomatal movement is the primary mechanism by which the plant exercises control over transpiration, two non-stomatal mechanisms have also been proposed. One of these envisages the development of a high resistance to vapour movement between the actual evaporative surfaces in the internal mesophyll cell walls and the natural cell wall surfaces, and has been referred to as “incipient drying”. The other envisages a substantial depression of the vapour pressure at the evaporative surfaces because of solute accumulation or steep local gradients of water potential. In the present paper evidence is presented which suggests that neither of these mechanisms is likely to occur under conditions of normal water supply, that is at water contents high enough to prevent permanent wilting. “Incipient drying” appears improbable because of the high permeability of the water pathway through the walls of the leaf cells and also because of the small void sizes in the interfibrillar spaces of the walls themselves. Significant vapour pressure depression also seems improbable, partly because the relatively high rates of water exchange between cells tend to prevent the development of steep local gradients of leaf water potential, and partly because excessive solute accumulation at the evaporative surfaces is prevented by back diffusion towards the xylem terminals. It is therefore concluded that non-stomatal mechanisms are unlikely to exercise significant control over transpiration under normal conditions. Only under conditions of extremely severe desiccation is direct control by such mechanisms possible, and then there is also likely to be complete stomatal closure.

Vapor pressures of ternary aqueous solutions of NaCl, KCl, Na2SO4, and MgSO4 at concentrations and temperatures of interest in desalination processes

Vapor pressures of ternary NaCl-KCl. NaCl-Na2SO4. and NaCl- MgSO4 solutions have been determined by differential vapor pressure measurements over the temperature range of 75 to 150 C. The solutions contained these compounds at concentrations corresponding to sea water and it concentrates up to five-fold concentration. The additivity rule for vapor pressure depressions, proposed by Robinson and Bower (l) was found valid over the entire temperature and concentration range investigated.

Studies on the ganglioside micelle

The molecular weight of β-ganglioside was measured by vapor pressure depression in a number of different solvents. The molecular weight was found to be near 1665, corresponding to a structure containing sphingosine, stearic acid, glucose, galactose, N-acetylgalactosamine, and two N-acetylneuraminic acid residues. In aqueous solution, the ganglioside associated to form a micelle structure with an aggregate weight of 200 000 or greater. The critical micelle concentration was found to be 1.0 · 10 −5 M. A discussion of these properties is presented.

Vapour Pressure Depression of the Saturated Solution Containing Inorganic Salts

Vapour Pressure Depression of the Saturated Solution Containing Inorganic Salts

Studies of Aggregation of Dodecylammonium Carboxylates in Carbon Tetrachloride by Infrared Absorption Spectra and Thermistors

Abstract Measurements of infrared absorption spectra and of vapor pressure depressions using a couple of matched thermistors were carried out with carbon tetrachloride solutions of dodecylammonium carboxylaf at varying concentrations. The absorption bands at 1710 and 1640 cm−1 were assigned to the carbonyl group of the monomer molecule which is formed by hydrogen bonding between amine and acid, and to the NH3+ group of ammonium salt resulting from the aggregation, respectively. The equation which was derived from the Beer’s law and the aggregation equilibrium made it possible to calculate the true aggregation number λ using the values of absorbance at each absorption band. Alternatively, the λ was calculated by means of the Kreuzer’s equation from the apparent mean aggregation number Z which was obtained using thermistors. The agreement between the λ’s obtained by the spectral and thermistor methods was satisfactory as for the order of magnitude. The cmc was tentatively estimated by both spectral and thermistor method. The agreement between the cmc’s obtained by these independent methods was good. But these cmc’s did not show good agreement with those obtained from solubilization.

THE MOLECULAR WEIGHT OF POLYETHYLENE AND OF OTHER HIGH-MOLECULAR-WEIGHT ORGANIC COMPOUNDS

The temperature range of the measurement of vapor-pressure depression using a sensitive differential mercury micromanometer has been extended, and the behavior of a series of polyethylene samples having a molecular-weight range of 2500 to 24,000 was examined in toluene solutions at 75 °C. Good agreement was obtained between vapor-pressure lowering and other means of determining number-average molecular weights of several special compounds.

Studies on Micelle Formation in Non-polar Solvent by Thermistor

Abstract The apparent mean aggregation number (Z) of dodecylammonium carboxylate in cyclohexane was obtained from the vapor pressure depression measurement by the use of a pair of thermistors. The monomer concentration (C1) was calculated from Kreuzer’s equations. The C1 was nearly independent of the concentration. The true aggregation number (λ) was obtained, assuming that the micelle is monodisperse. The cmc extraploated from C1 agreed approximately with those by other methods. The change of the heat content associated with micelle formation was calculated from the change of the cmc with the temperature and from the temperature dependence of the equilibrium constant for the λ-mer aggregation. Both agreed roughly with each other.

Sorption of Water by Rubber Closures for Injections II : Effects of Vapor Pressure, Bisulfite, and Washing Treatments

The effect of vapor pressure lowering, bisulfite, and washing procedures on the sorption of water by rubber closures has been studied. A logarithmic relationship between sorption of water by rubber closures and depression of vapor pressure due to inorganic salts was derived. An apparatus suitable for vapor pressure measurements of solutions is described. Sulfur dioxide was shown to be the cause of the increased sorption exhibited from bisulfite solutions. The attempt to evaluate washing procedures by means of sorption measurements was not successful.

Osmotic pressures in the henʼs egg

In a recent paper Howard (1932) claims to have shown, by three methods, that the "expected" osmotic equilibria exist between the yolk and white of a hen's egg. Johlin (1933) has criticized her technique of cryhydric measurement and re-asserted that the yolk and white of an egg hive different values for depression of freezing point. Although Needham (1931) and Meyerhof (1931) have considered the possibility of the outer layer of yolk having a lower osmotic pressure than the inner, Howard gives no experimental evidence indicating the existence of an osmotic gradient within the yolk. The methods she used being apparently incapable of showing the difference in osmotic pressure between the whole yolk and the whole white of an egg were presumably unable also to detect the osmotic gradient in the yolk. Grollman's (1931) criticisms of the Hill thermo-electric method for the measurement of vapour pressures when employed with viscous solutions were repeated by Howard, with no other evidence than that it gave results which disagreed with her own. In particular, Bateman's low vapour pressure depression found in mixtures of egg yolk and egg white are declared to be incompatible with high vapour pressure depressions for yolk. It is strange that in the differentiation of the properties of egg yolk and white so many authors should have considered the yolk as homogeneous. It is a well-known fact that the formation of an egg yolk occurs by daily deposits in the ovary of the hen. These extend over several days and that the integrity of the daily deposit is maintained more or less for many days is evidenced by observation of the spherical zones in the yolk of a frozen egg that has been sectioned. Also it is easy to withdraw from the centre of the yolk, using a fine pipette, white yolk which is different chemically from the surrounding yellow yolk. Since no membrane is known to separate these two kinds of yolk nor the daily deposit of yolk, the existence of this non-homogeneity within the yolk must be an indication of the slowness of equilibration inside a hen's egg. Hence, when one speaks of the difference in osmotic pressure of average egg white and average egg yolk, no conclusions can be drawn logically regarding the difference in osmotic pressure on opposite sides of the vitelline membrane. As the Hill thermoelectric method of measuring vapour pressure requires but small quantities of solution, it was of interest to use this micro method to study the difference in osmotic pressures of samples of yolk and white obtained on opposite sides of the membrane.

THE VAPOUR PRESSURES OF AQUEOUS SOLUTIONS WITH SPECIAL REFERENCE TO THE PROBLEM OF THE STATE OF WATER IN BIOLOGICAL FLUIDS

DATA FOR THE DEPRESSION OF VAPOUR PRESSURE ARE PRESENTED FOR THE FOLLOWING AQUEOUS SOLUTIONS: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl(2) (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances-LiCl and CaCl(2)-the principle of the additive nature of colligative properties is also only approximately true-except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances.

Societies and Academies

Societies and Academies

The state of water in muscle and blood and the osmotic behaviour of muscle

In the course of the investigation described in the preceding paper by Hill and Kupalov it became necessary to determine the amount of “free” water in muscle, i.e. , the weight of water per gramme of muscle which is capable of dissolving in a normal manner (with the normal depression of vapour pressure) substances added to it. For many years, chiefly on the evidence of the experiments of Overton (1902), it has been commonly supposed that a large proportion of the water of muscle exists in some “bound” form, incapable of taking part in the osmotic changes which occur when the tissue is immersed in hypoor hyper-tonic solutions. From the fact that a muscle swells to much less than twice its initial weight when immersed in a solution of half the initial osmotic pressure Overton concluded “dass nicht das gesammte im Muskel befindliche Wasser in der Form eines Lösungsmittels enthalten sein kann.” I have confirmed Overton’s experiments (see below) but believe that a very different explanation of them is necessary.