70. The vapour pressure of water over aqueous solutions of the chlorides of the alkaline-earth metals. Part II. Deviations from Raoult's law, as indicated by the molecular lowering of vapour pressure and van 't Hoff coefficients; with theoretical discussion

1932 ◽  
pp. 566 ◽  
Author(s):  
Jack Reginald Irons Hepburn
Keyword(s):  
Aqueous Solutions ◽  
Vapour Pressure ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
Theoretical Discussion ◽  
Raoult’S Law ◽  
Raoult's Law

scholarly journals Raoult’s law revisited: accurately predicting equilibrium relative humidity points for humidity control experiments

2016 ◽  
Author(s):  
Michael G. Bowler ◽  
David R. Bowler ◽  
Matthew W. Bowler
Keyword(s):  
Relative Humidity ◽  
Vapour Pressure ◽  
Control Device ◽  
Raoult’S Law ◽  
Simple Argument ◽  
Humidity Control ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour ◽  
Equilibrium Relative Humidity ◽  
Raoult's Law

AbstractThe humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, which often leads to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals on a beamline have led to this technique being increasingly adopted, as experiments become easier and more reproducible. Matching the relative humidity to the mother liquor is the first step to allow the stable mounting of a crystal. In previous work, we measured the equilibrium relative humidity for a range of concentrations of the most commonly used precipitants and showed how this related to Raoult’s law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between measured values and those predicted by theory could not be explained. Here, we have used a more precise humidity control device to determine equilibrium relative humidity points. The new results are in agreement with Raoult’s law. We also present a simple argument in statistical mechanics demonstrating that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult’s Law. The same argument can be extended to the case where solvent and solute molecules are of different size, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding samples.SynopsisThe equilibrium relative humidity values for a number of the most commonly used precipitants in biological macromolecule crystallisation have been measured using a new humidity control device. A simple argument in statistical mechanics demonstrates that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution (Raoult’s Law). The same argument can be extended to the case where solvent and solute molecules are of different size.

scholarly journals Die Kristallstrukturen von Strontium- und Bariumhexacyanoferrat(III)-Hexamethylentetramin-Hydraten. Strukturmodell für Additionsverbindungen der Alkali- und Erdalkalimetallhexacyanoferrate mit Hexamethylentetramin / The Crystal Structures of Hydrates of Strontium and Barium Hexacyanoferrate(III) with Hexamethylenetetramine. Structural Model for Adducts of the Hexacyanoferrates of Alkaline and Alkaline Earth Metals with Hexamethylenetetramine

1989 ◽  
Vol 44 (5) ◽  
pp. 519-525 ◽  
Author(s):  
Hans-Jürgen Meyer ◽  
Joachim Pickardt
Keyword(s):  
Aqueous Solutions ◽  
Crystal Structures ◽  
General Formula ◽  
Alkaline Earth ◽  
Structural Model ◽  
Earth Metal ◽  
Alkaline Earth Metals ◽  
Alkaline Earth Metal ◽  
Monoclinic Space Group ◽  
Space Group

By reaction of methanolic solutions of hexamethylenetetramine with aqueous solutions of hexacyanoferrates(III) of strontium and barium resp., crystals of the compounds were obtained. Sr3[Fe(CN)6]2 · 3 C6H12N4 · 18 H2O, tetragonal, space group P42/nmc, Z = 4, a = 1931.8(4), c = 1579.9(4) pm, 1358 reflections. R = 0.066. Ba3[Fe(CN)6]2 · 2 C6H12N4 · 11 Η2Ο. monoclinic. space group P21/n, Ζ = 2, a = 1148.0(4), b = 1369.7(4), c = 1584.5(4) pm, γ = 95.79(3)°, 2583 reflections, R = 0.057. The crystal structures of these adducts are compared with those of other hexamethylenetetramine adducts of alkaline and alkaline earth metal hexacyanoferrates of the general formula M,[Fe(CN)6]y · zC6H12N4 · vH2O recently investigated by us. A structural model for the adducts is presented.

Vapour Pressure and Activity Coefficients of Dilute 2,2,4 Trimethylpentane(Isooctane)-Acetone Mixtures

1970 ◽  
Vol 25 (1) ◽  
pp. 45-47
Author(s):  
J. Edwards ◽  
M.V. Encina
Keyword(s):  
Activity Coefficients ◽  
Vapour Pressure ◽  
Pressure Measurements ◽  
Raoult’S Law ◽  
Azeotropic Point ◽  
Raoult's Law

Abstract Vapour pressure measurements are carried out to test Raoult's law at extreme concentrations, and the deviations are reported. - The azeotropic point is measured and qualitative discussions are presented.

Vapour pressures of aqueous solutions of (Ag, Tl, Cd)NO3 at 98.5 °C. I. Brunauer–Emmett–Teller isotherms

1978 ◽  
Vol 56 (3) ◽  
pp. 348-351 ◽  
Author(s):  
James Malcolm Sangster ◽  
Marie-Christine Abraham ◽  
Maurice Abraham
Keyword(s):  
Aqueous Solutions ◽  
Water Concentration ◽  
Raoult’S Law ◽  
Crossover Point ◽  
Additivity Rules ◽  
Static Technique ◽  
Bet Equation ◽  
Raoult's Law

Vapour pressures of aqueous solutions of the mixed melt AgNO3 + TlNO3 + Cd(NO3)2 have been measured at 98.5 °C by the static technique. The Ag/Tl mole ratio was fixed at 1.06, and the mole fractions Cd/(Ag + Tl + Cd) of Cd in the melt were 0, 0.05, 0.075, 0.10, and 0.125. Adapted BET isotherms and their constants were obtained for each of the five melt mixtures. It has been shown, in the present study, from the BET equation itself, and verified experimentally, that certain Systems can give rise to a 'crossover point', that is, a reversal of sign of the deviation from Raoult's law. The BET constants of the systems conform to simple additivity rules. The water concentration range over which the BET equation is valid is unexpectedly wide.

scholarly journals About perspectives of photocatalytic reduction of metals from natural and man-made solutions

2020 ◽  
Author(s):  
Д.С. ШТАРЕВ ◽  
А.В. ШТАРЕВА ◽  
Н.В. БЕРДНИКОВ
Keyword(s):  
Aqueous Solutions ◽  
Visible Light ◽  
Alkaline Earth ◽  
Selective Reduction ◽  
Alkaline Earth Metals ◽  
Photocatalytic Reduction ◽  
Experimental Results ◽  
Experimental Conditions

Обсуждаются результаты экспериментов по фотокаталитическому восстановлению металлов из растворов в присутствии фотокатализаторов видимого света на основе висмутатов щелочноземельных металлов. Показано, что наибольшее количество изученных металлов успешно восстанавливается из растворов в присутствии Ca5Bi14O26. Наименее подверженными фотокаталитическому восстановлению оказались Li, B, Na, Al, Ca, Fe, Ba, W, Re. Наименее эффективным для восстановления металлов из растворов при данных условиях эксперимента оказался фотокатализатор Sr3Bi2O6. Обоснована перспективность фотокатализа для селективного восстановления и выделения ниобия и тантала из водных растворов. Большинство элементов после восстановления удаляются из раствора, по-видимому, оседая на фотокатализаторе и стенках реактора. Восстановленное золото коагулирует в частицы, образующие в растворе взвесь. Результаты экспериментов свидетельствуют о перспективности исследования фотокатализаторов видимого света на основе висмутатов щелочноземельных металлов для разработки технологий очистки природных и техногенных растворов с получением из них ценных компонентов. The results of experiments on the photocatalytic reduction of metals from solutions in the presence of visible light photocatalysts based on bismuthates of alkaline earth metals are discussed. It is shown that the largest number of studied metals is successfully reduced from solutions in the presence of Ca5Bi14O26. The least prone to photocatalytic reduction were Li, B, Na, Al, Ca, Fe, Ba, W, Re. The Sr3Bi2O6 photocatalyst was the least effective for the recovery of metals from solutions under these experimental conditions. The prospects of photocatalysis for the selective reduction and isolation of niobium and tantalum from aqueous solutions are justified. Most of the elements after recovery are removed from the solution, apparently, deposited on the photocatalyst and the walls of the reactor. Reduced gold coagulates into particles, forming a suspension in solution. The experimental results indicate the promise of research on visible-light photocatalysts based on bismuthates of alkaline earth metals for the development of technologies for the purification of natural and man-made solutions to produce valuable components from them.

Sign in / Sign up

Export Citation Format

Share Document