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.

The entropy of liquid mixtures: I. The theory of Raoult's Law

1941 ◽  
Vol 60 (2) ◽  
pp. 76-84 ◽  
Author(s):  
A. J. Staverman ◽  
J. H. van Santen
Keyword(s):  
Liquid Mixtures ◽  
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.

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