摘要:

The X-radiolysis of water vapor containing methanol at 125 °C and 1 atm pressure has been studied alone and in the presence of some electron and hydrogen atom scavengers. In water vapor containing methanol only, a plateau valueG(H2) = 7.9 ± 0.3 is obtained at all methanol concentrations above 0.5 mole %. Addition of propylene drastically reduces this yield due to efficient scavenging of hydrogen atoms, and values for the total number of H atoms from all precursorsg(H)t = 7,5 ± 0.2 andare deduced from the competition. An unscavengeable hydrogen yieldg(H2) ~ 0.5 is also indicated in mixtures containing propylene. Nitrous oxide and sulfur hexafluoride are found to scavenge electrons efficiently in water vapor containing methanol and the number of hydrogen atoms arising from electron–positive ion recombination is estimated to have a valueG = 2.2 ± 0.6. The number of hydrogen atoms arising from processes not involving electrons isg(H) = 5.2 ± 0.3. Carbon tetrachloride reacts efficiently with both electrons and hydrogen atoms, withk(H + CH3OH)/k(H + CCl4) = 0.085. Values ofg(H) = 4.9 ± 0.5 andg(H2) = 0.8 ± 0.2 are deduced from mixtures containing carbon tetrachloride.

ISSN:0008-4042    

DOI:10.1139/v68-325

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Standard heats of ionization of ortho-, meta-, and para-toluidinium ions in water at 25 °C have been determined in a high precision solution calorimeter. Entropies of ionization have been calculated from these heats and well-defined free energy changes. As predicted by theory, a linear relation is found between ΔS0Ionand ΔG0Ionand between ΔH0Ionand ΔS0Ionfor these compounds.

ISSN:0008-4042    

DOI:10.1139/v68-326

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A novel type of vertically oscillating bob viscometer for liquids is described. The mathematical theory of a solid sphere oscillating in a viscous liquid is developed, and results in an exact equation depicting the relationship between the logarithmic decrement of the oscillations of the sphere and the viscosity of the liquid surrounding the bob. The use of this technique for the determination of absolute viscosity of liquids is demonstrated. Using five sample liquids, at room temperature, the average error between the absolute viscosities determined and those of previous measurements is ± 1.5%.The viscometer consists of a quartz spring, which suspends a solid gold sphere, hanging vertically. The oscillations of the system are sensed by electrically recording the output of a linear variable differential transformer, the core of which forms a part of the oscillating system. The oscillations are stimulated electrically; the positioning of the transducer core is precisely adjustable with the use of an electric motor driven mechanism. Thus, the viscometer can be entirely remotely controlled and is, therefore, recommended for experimental situations which make the liquid not easily accessible, e.g. inside furnaces, pressure vessels, vacuum chambers, etc.

ISSN:0008-4042    

DOI:10.1139/v68-327

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The equivalent conductivities of tetramethylammonium iodide, tetraethylammonium iodide, and tetra-n-propylammonium iodide in acetone solution were determined at concentrations from 1 to 10 × 10−4 mole/liter and at temperatures of 25 to 55 °C and pressures from atmospheric to 1.1 kbar. The concentration dependence of the equivalent conductivities was analyzed by the Shedlovsky method. Limiting equivalent conductivities and ion-pair dissociation constants are tabulated.

ISSN:0008-4042    

DOI:10.1139/v68-328

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The limiting equivalent conductivities of tetramethylammonium iodide, tetraethylammonium iodide, and tetra-n-propylammonium iodide in acetone solution have been interpreted in terms of activated-complex theory; the energies of activation for conductivity at constant pressure and at constant volume, and the volumes of activation for conductivity, were calculated.The hole free-volume theory of liquids has been discussed and found to give a satisfactory explanation for the observed pressure and temperature coefficients of conductivity, viscosity, and self-diffusion in several solvents. The magnitude of the limiting ionic equivalent conductivity has been shown to depend in a critical way on the ionic radius and on the relative strengths of the ion–solvent and the solvent–solvent interactions.

ISSN:0008-4042    

DOI:10.1139/v68-329

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The ion-pair dissociation constants determined from a Shedlovsky analysis of conductivity (see Part I) were used to calculate the enthalpy, the internal energy at constant volume, the entropy, and the volume of dissociation of tetramethylammonium iodide, tetraethylammonium iodide, and tetra-n-propylammonium iodide ion pairs in acetone solution. The sign and magnitude of these parameters over the range of conditions investigated, temperature 25 to 55 °C and atmospheric to 1.1 kbar pressure, indicated that the free ions in acetone solution are extensively solvated and that, depending on the conditions, solvent-shared or solvent-separated ion pairs are formed.

ISSN:0008-4042    

DOI:10.1139/v68-330

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The general trend of the theoretical results obtained by Tung on simulated fractionations is verified experimentally, showing that the sharpness of the fractions and the variation of the sharpness in the different fractions of a given fractionation are very much dependent on the fractionation conditions and especially on the polymer starting concentration. For very low starting concentration, the middle fractions can be considered as being monodisperse as far as polydispersity detection by light scattering is concerned. The ratiofor these fractions can be used as a reference for polydispersity characterization of other samples of the same polymer. The comparison of this ratio to the same ratio obtained on a polydisperse sample yields. Results obtained in this way for a moderately sharp fractionation are in good accord with the theoretical predictions of Tung.

ISSN:0008-4042    

DOI:10.1139/v68-331

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

ΔHand ΔSwere obtained by pKameasurements in water at different temperatures for a series of dihydroxylated tertiary amines. The thermodynamic factors seem to confirm that the diminution in basicity introduced by long chain substituents is caused by frontal hindrance to solvation, accompanied by a new type of back-strain. With short chain substituents, the formation of intramolecular hydrogen bonds can be seen by the variations of the entropy factor.

ISSN:0008-4042    

DOI:10.1139/v68-332

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A semi-empirical P.P.P. type s.c.f.m.o. method has been developed to calculate, with practical accuracy, heats of atomization (at 25 °C), bond lengths, and resonance energies of benzenoid hydrocarbons. Sigma bond energiesEσbare estimated simultaneously with the pi bond energiesEπbin this method. Self-consistent field bond lengths are obtained, by minimization of the total bond energy,Eσb + Eπb, with respect to each individual bond length. The empirical resonance energies are calculated and a new term, the stabilization energy per CC bond, is introduced.

ISSN:0008-4042    

DOI:10.1139/v68-333

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Accurate heats of atomization and bond lengths are calculated for several polyenes and polyphenyls, using the s.c.f.–l.c.a.o.–m.o. method described in Part I (1). Localization of π and σ bonds is found in the linear polyenes and in the diphenyl-substituted polyenes. The estimated stabilization energy per CC bond (SECC) gives a direct measure of the π electron conjugation and σ bond compression. Conjugation stabilization and steric hindrance are analyzed in 1,3-butadiene and biphenyl; the predicted geometries are in good agreement with experimental results. The minimum energy for any planar structure is found to be associated with the s.c.f. calculated bond lengths. The validity of pi bond order as a measure of molecular stability in the polyphenyls is discussed.

ISSN:0008-4042    

DOI:10.1139/v68-334

出版商:NRC Research Press    

年代:1968

数据来源: NRC