Heats of mixing. V. Systems of n-alcohols with n-hexane

1964 ◽  
Vol 17 (10) ◽  
pp. 1106 ◽  
Author(s):  
I Brown ◽  
W Fock ◽  
F Smith
Keyword(s):  
Measured Data ◽  
Alcohol Molecule ◽  
Hydroxyl Groups ◽  
Free Energies ◽  
Dilute Solutions ◽  
Chain Molecules ◽  
Heats Of Mixing ◽  
Enthalpy Difference ◽  
Higher Temperature ◽  
Generally True

Heats of mixing have been measured at 25�, 35�, and 45� for mixtures of ethanol, propan-1-ol, butan-1-ol, hexan-1-ol, and octan-1-ol with n-hexane and for methanol with n-hexane at 45�. These heats of mixing were found to increase with an increase in temperature and to decrease with an increase in the size of the alcohol molecule. They showed anomalies for the systems containing methanol and ethanol. An explanation of these anomalies has been given. The contribution of the hydroxyl groups to the enthalpy of any mixture of a n-alcohol with a n-alkane is defined as the enthalpy change on replacing the alcohol by its homomorphic alkane. The experimental results given here are consistent with the postulate that the contribution of the hydroxyl groups (per mole of alcohol) to the enthalpy depends only on the ratio of the number of hydroxyl groups to that of hydrocarbon units in the mixture. This postulate, if generally true, can be used for the prediction of the heats of mixing of any n-alcohol with a n-alkane and of the enthalpy difference between any n-alcohol and its liquid homomorphic alkane. Other data support the conclusion that the postulate holds for all concentrations of alcohol, but show that the analogous postulate applied to free energies holds only for infinitely dilute solutions of alcohols. The interaction of the hydroxyl groups with the hydrocarbon units contribute -7.8 and -4.5 kJ/mole of alcohol to the enthalpies and free energies respectively of these infinitely dilute solutions. The required values of the heats of mixing of the lower alkanes with n-hexane were estimated from the enthalpies of the alkanes using the principle of congruence; these were found to be appreciable and negative. They are in sign agreement with values extrapolated, from measured data at a higher temperature, using a principle of corresponding states for chain molecules.

Theoretical Investigation of the CO2 Capture Properties of γ-LiAlO2 and α-Li5AlO4

2019 ◽  
Vol 11 ◽  
Author(s):  
Yuhua Duan
Keyword(s):  
Co2 Capture ◽  
Wide Band ◽  
Band Gaps ◽  
Lithium Aluminate ◽  
Free Energies ◽  
Solid Sorbents ◽  
Lower Temperature Range ◽  
Higher Temperature ◽  
Valence Bands ◽  
Lower Temperature

: Lithium aluminate has attracted researchers’ interests due to its wide applications. By combining electronic structural and lattice phonon thermodynamic calculations, the CO2 capture properties of γ-LiAlO2 and α-Li5AlO4 are investigated. Both γ-LiAlO2 and α-Li5AlO4 are insulators with wide band gaps of 4.70 and 4.76 eV respectively. Their 1st valence bands just below the Fermi level are mainly formed by p orbitals of Li, O and Al as well as s orbital of Li. By increasing the temperature from 0 K up to 1500 K, their phonon free energies are decreased while their entropies are increased. Targeting on developing post- and pre-combustion CO2 capture technologies, the obtained results indicated that γ-LiAlO2 is thermodynamically favorable to capture CO2 at lower temperature range (500-800 K) while α-Li5AlO4 could capture CO2 at higher temperature (800-1000 K) range in comparison with other solid sorbents, such as pure Li2O, Li4SiO4 and Li2ZrO3.

CYCLODEXTRIN NANOTUBE INDUCED BY 4,4′-BIS(2-BENZOXAZOLYL) STILBENE

2006 ◽  
Vol 05 (02n03) ◽  
pp. 213-218 ◽  
Author(s):  
AIHUA WU ◽  
XINGHAI SHEN ◽  
HONGCHENG GAO
Keyword(s):  
Hydrogen Bonding ◽  
Temperature Effect ◽  
Fluorescence Anisotropy ◽  
Ph Effect ◽  
Effect Study ◽  
Hydroxyl Groups ◽  
Higher Temperature

The formation of β- and γ-cyclodextrin (CD) nanotubes induced by the molecule 4,4′-bis(2-benzoxazolyl) stilbene (BOS) was investigated by fluorescence anisotropy. Using the Perrin–Webber formula, the average number of cyclodextrin (n CD ) in each nanotube was estimated and the results suggested that the n CD value in the γ-CD system is larger than that in the β-CD system. Hydrogen-bonding between the hydroxyl groups of neighboring CDs was found to be an important contribution to the formation of cyclodextrin nanotube on the basis of the pH effect study. The temperature effect study showed that this nanotube was thermostable at T ≤ 303 K , while it was gradually collapsed at higher temperature.

Rubber Elasticity and Gas Elasticity

1939 ◽  
Vol 12 (2) ◽  
pp. 124-129
Author(s):  
H. Mark
Keyword(s):  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Absolute Temperature ◽  
Rubber Elasticity ◽  
Chain Molecules ◽  
Internal Mobility ◽  
Higher Temperature ◽  
Coefficient Of Elasticity ◽  
Polyacrylic Ester ◽  
High Degree

Abstract All substances which are composed of long mobile chains show one peculiar property, highly reversible elasticity. Even though the range of temperature of this property may be notably variable (in the case of polyvinyl alcohol and rubber at about room temperature, in the case of polystyrene, sulfur, or Thiokol only at a higher temperature) still it is to be noted that for rubber-like elasticity the presence of long flexible chains is an indispensable factor. Thus, typical rubber elasticity occurs in polyvinyl alcohol (Vinarol), polybutadiene (Buna), polymethyl-butadiene (methyl rubber), polyacrylic ester and also in its mixed polymerisate with vinyl chloride. This type of elasticity occurs also in sinew fibrin and muscle fibrin, in polychlorobutadiene (Neoprene, Sovprene), in polyethylene sulfide (Thiokol, Baerite), polyphosphornitrile chloride and finally in vulcanized oils (factice) and also in elastic sulfur. In the cases so far examined (natural rubber, Buna, methyl rubber), it has been found that the coefficient of elasticity increases proportionally to the absolute temperature, and that during the stretching heat is evolved. This behavior is contrary to that of normal elastic materials, steel, quartz, glass, etc. It is striking that the substances which have this property of highly reversible (rubber-like) stretching are widely different chemically. This tempts one to ascribe that property to the similarity of their construction. For example, all the substances mentioned consist of long chain-molecules, which display a high degree of internal mobility. The number of members in these chains varies from 102 to 104 and their mobility is due to the kind of linkage between the members, mostly simple C—C bonds.

THE SURFACE TENSION OF SLIGHTLY SOLUBLE FATTY ACIDS

1946 ◽  
Vol 24a (1) ◽  
pp. 8-14 ◽  
Author(s):  
D. G. Douglas ◽  
C. A. MacKay
Keyword(s):  
Fatty Acids ◽  
Surface Tension ◽  
Aqueous Solutions ◽  
Capillary Rise ◽  
Stable State ◽  
Melting Points ◽  
Considerable Time ◽  
Dilute Solutions ◽  
Chain Molecules ◽  
Capillary Rise Method

Surface tension measurements have been made on normal heptylic, pelargonic, capric, and lauric acids above their melting points and on aqueous solutions of heptylic, pelargonic, capric, and undecylic acids, at various concentrations. A modified capillary rise method was employed. The results indicate that the surface does not reach the stable state at once but requires considerable time, being slower for more dilute solutions and longer chain molecules. Evidence is given for the existence of a monolayer of closely packed molecules, with long axes perpendicular to the surface, each molecule occupying an area of approximately 25 Å for heptylic acid.

Thermodynamic Properties of Dilute Solutions of Hydrogen in Glassy PD.80SI.20

1981 ◽  
Vol 8 ◽  
Author(s):  
R.S. Finocchiaro ◽  
C.L. Tsai ◽  
B.C. Giessen
Keyword(s):  
Thermodynamic Properties ◽  
Composition Range ◽  
Volumetric Method ◽  
Vapor Pressures ◽  
Free Energies ◽  
Positive Deviation ◽  
Dilute Solutions ◽  
Maximum Value ◽  
Statistical Mechanical ◽  
Partial Molar Enthalpies

ABSTRACTEquilibrium vapor pressures of dilute solutions of hydrogen in glassy Pd.80Si.20 have been measured from 10–90°C and at hydrogen pressures P of 1–100 torr. Under these conditions the ratio of hydrogen to alloy, x as determined by a volumetric method, reaches a maximum value of 0.0070. Over this range of x, the system exhibits a positive deviation from Sieverts' Law; isotherms were analyzed in terms of Lacher's modified statistical mechanical theory of hydrogen in palladium. The data were used to calculate relative partial molar enthalpies, excess entropies, and excess free energies for the formation of the solid solutions. The thermodynamic properties were found to vary with hydrogen content over the composition range studied.

The Properties of Polymers in Solution. X. Ultrafiltrations of Rubber Solutions

1939 ◽  
Vol 12 (4) ◽  
pp. 774-777
Author(s):  
Kurt H. Meyer ◽  
Jean Jeannerat
Keyword(s):  
Colloidal Suspensions ◽  
Spherical Particles ◽  
Accurate Data ◽  
Colloidal Solutions ◽  
Dilute Solutions ◽  
Chain Molecules

Abstract It is a recognized fact that ultrafiltration is one of the most valuable methods for the study and treatment of colloidal suspensions formed of compact spherical particles. Not only is it possible to separate this type of particle from a solvent by means of a suitable ultrafilter, but it is also possible to determine the size of the particles by means of calibrated ultrafilters. Up to the present time, however, ultrafiltration has been utilized very little in the study of chain molecules, and no accurate data are available on the behavior of colloidal solutions of chain molecules during ultrafiltration. In the following discussion, the results of some experiments on the ultrafiltration of rubber solutions are described. Dilute solutions of rubber in toluene can be separated completely into rubber and solvent by ultrafiltration under pressure through fine ultrafilters with pores as fine as about 50 ḿ (“Fine” Cellafiltres and Membranfiltres). Solutions of crepe and solutions of masticated rubber give the same results.

scholarly journals In situ U g-value measurement on three different glazing types

2021 ◽  
Vol 2069 (1) ◽  
pp. 012134
Author(s):  
F Paschke ◽  
N Bishara ◽  
I Schulz ◽  
C Kocer ◽  
J Schneider ◽  
...  
Keyword(s):  
Measured Data ◽  
Environmental Condition ◽  
High Thermal Resistance ◽  
Higher Temperature ◽  
G Value ◽  
One Year ◽  
Value Measurement ◽  
Resistance To Heat ◽  
Glass Unit

Abstract This study presents in situ monitoring data of three different glazing systems over a period of one year. An insulated glass unit (IGU), a Vacuum Insulated Glass hybrid unit (VIG-hybrid) and an opaque architectural insulation module (AIM) were monitored under the equivalent environmental condition in this study. Different issues were observed and analyzed. It was found that the Ug-value cited by the manufacturers agrees with the Ug-values derived from the measured data, to within less than 5 % for the IGU and the VIG-hybrid. The consistency of the Ug-value of each glazing types one year after the start of monitoring was validated for similar environmental conditions. Depending on the magnitude of the resistance to heat flow, an increasing Ug-value was observed for a higher temperature difference between the inside and outside environments. The effect is much more significant for the glazing type with the largest Ug-value (IGU) and less significant for the glazing types with a high thermal resistance (VIG-hybrid, AIM).

Dielectric relaxation in dilute solutions of polar chain molecules

1957 ◽  
Vol 23 (103) ◽  
pp. 211-221 ◽  
Author(s):  
L. K. H. Van Beek ◽  
J. J. Hermans
Keyword(s):  
Dielectric Relaxation ◽  
Dilute Solutions ◽  
Chain Molecules
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