scholarly journals The Vapor-pressure Method of Determining Molecular Weights

1897 ◽  
Vol 1 (12) ◽  
pp. 753-759 ◽  
Author(s):  
W. R. Orndorff ◽  
H. G. Carrell
Keyword(s):  
Vapor Pressure ◽  
Molecular Weights ◽  
Pressure Method

Thermodynamics of liquid In-Ga-Zn alloys determined by vapor pressure method

Calphad ◽  
2020 ◽  
Vol 71 ◽  
pp. 102198 ◽  
Author(s):  
Sebastian Kulawik ◽  
Andrzej Zajączkowski ◽  
Adam Dębski ◽  
Władysław Gąsior ◽  
Wojciech Gierlotka
Keyword(s):  
Vapor Pressure ◽  
Pressure Method ◽  
Zn Alloys

Thermodynamics of liquid Ga-Sn-Zn alloys determined by vapor pressure method

2020 ◽  
Vol 300 ◽  
pp. 112310 ◽  
Author(s):  
S. Kulawik ◽  
A. Zajączkowski ◽  
A. Dębski ◽  
W. Gąsior ◽  
W. Gierlotka
Keyword(s):  
Vapor Pressure ◽  
Pressure Method ◽  
Zn Alloys

Correction for loss of CO2 from blood during measurement of osmotic pressure

1978 ◽  
Vol 44 (3) ◽  
pp. 474-478 ◽  
Author(s):  
S. S. Khosla ◽  
A. B. DuBois
Keyword(s):  
Vapor Pressure ◽  
Blood Sample ◽  
Osmotic Pressure ◽  
Freezing Point ◽  
Gas Mixture ◽  
Sample Holder ◽  
Freezing Point Depression ◽  
Pressure Method ◽  
Sample Chamber

During osmolality measurement by the vapor pressure method, exposure of the blood sample to air lowers the blood CO2 content and hence osmolality. A modification of the sample holder of a vapor pressure osmometer is described allowing exposure of the blood sample to a gas mixture with known concentration of CO2 and O2 while inside the closed sample chamber. This restores its CO2 content and hence osmolality. Data are presented comparing the unmodified and modified vapor pressure method with the freezing point depression method. A table was prepared for further correction of osmolality in case the blood's PCO2 differs from that of the gas mixture.

Behavior of Rubber Hydrocarbon in a Molecular Still

1939 ◽  
Vol 12 (4) ◽  
pp. 789-793 ◽  
Author(s):  
W. Harold Smith ◽  
Henry J. Wing
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
High Molecular Weight ◽  
Molecular Species ◽  
Decomposition Temperature ◽  
Sedimentation Equilibrium ◽  
Chain Molecules ◽  
Molecular Weights ◽  
Average Value ◽  
Long Chain

Abstract Some investigators believe that rubber consists of associated molecules, and others accept Staudinger's view that long-chain molecules are formed by polymerization. Pummerer, Andriessen and Gündel have obtained a molecular weight as low as 600. Meyer and Mark believe that it is approximately 5,000, although they calculated on the basis of osmotic pressures values as high as 350,000. They, as well as Pummerer, consider that rubber is an associated colloid and that high molecular weights are caused by aggregates, sometimes called micelles. Staudinger, however, considers that the long-chain rubber molecule itself has a molecular weight of 200,000 or even 350,000, and that products with lower values, which may be formed in rubber, result from degradation. if the molecules are small it might be possible to distil them if their vapor pressure could be sufficiently increased, but none would distil without decomposition if the molecules are very large. Because the vapor pressure of rubber below its decomposition temperature is low, it appeared of interest to attempt to distil the material in a molecular still. Paraffin wax and sugar, both substances of relatively high molecular weight, have been successfully distilled in this type of apparatus. Subsequent to the work described in this paper, the molecular weight of sol rubber prepared at this Bureau was determined by Kraemer and Lansing of E. I. du Pont de Nemours & Co., Inc. They used the Svedberg method of sedimentation equilibrium in an ultracentrifuge with ethereal solutions of sol rubber. The temperature of the solutions during determinations was approximately 10° C, and an average value of 460,000 was obtained. There was evidenced of a mixture of molecular species.

THE MOLECULAR WEIGHT OF POLYVINYL ACETATE

1958 ◽  
Vol 36 (3) ◽  
pp. 543-549 ◽  
Author(s):  
A. F. Sirianni ◽  
R. Tremblay ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Polyvinyl Acetate ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Approximate Molecular Weight ◽  
Low Degrees ◽  
Made In

The molecular weights of a series of unfractionated polyvinyl acetates of low degrees of polymerization have been measured by determining the lowering of the vapor pressure of their solutions. An approximate molecular-weight range of 5000–40,000 was examined. While most of the determinations were made in benzene solutions at 55 °C., other solvents and temperatures were used. Anomalous results were obtained with one sample of fractionated material.

Sign in / Sign up

Export Citation Format

Share Document