摘要:

The recombination of methyl and benzyl radicals has been studied over the temperature range 529 to 799 °K. The Arrhenius parameters for the recombination reaction are logA(cc mole−1s−1) = 11.20,E = 0.20 kcal mole−1. The frequency factor at 1 000 °K for the reverse reaction, the dissociation of ethyl benzene, is calculated to be logA(s−1) = 14.9. A value of 70.5 kcal mole−1has been estimated forD(C6H5CH2—CH3).

ISSN:0008-4042    

DOI:10.1139/v67-095

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Thermogravimetric (t.g.a.) and differential thermal analyses (d.t.a.) of ε-Zn(OH)2, Zn5(OH)8Cl2.H2O, β-ZnOHCl, and ZnOHF are reported and discussed. The results show that the replacement of a hydroxyl group by a halogen group contributes to greater thermal stability of the hydroxy compound. The thermal stability increases in the order ε-Zn(OH)2 < Zn5(OH)8Cl2 < β-ZnOHCl < ZnOHF.The hydroxy compounds decompose via dehydration in the initial step followed by hydrolysis of the zinc halide and (or) volatilization of the zinc halide yielding an ultimate residue of zinc oxide and trace quantities of the zinc halide.

ISSN:0008-4042    

DOI:10.1139/v67-096

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Infrared spectra of ε-Zn(OH)2, β-ZnOHCl, ZnOHF, Zn5(OH)8Cl2, and Zn5(OH)8Cl2·H2O and their deuterated analogues in the range 2.5–16 μ are reported for the first time. The effects of substituting a halogen for an OH group in Zn(OH)2are (i) sharper OH stretching absorption bands, (ii) splitting of bands involving OH to give distinct doublets in ZnOHF and Zn5(OH)8Cl2, indicating strong intermolecular coupling, and (iii) shift of the OH stretching vibration to a higher frequency. Strong absorption bands are observed in the region of 695–780 cm−1for all compounds and also near 1 020 ± 30 cm−1in all cases except ZnOHCl. All the observed bands are displaced to lower frequencies by the deuterated analogues, withvH/vDratios in the range 1.30–1.36. A cursory interpretation of the spectra of ZnOHCl and ZnOHF is given in terms of a planar molecule ofCssymmetry, but the unambiguous assignment of the bands must await a site group or group factor analysis.

ISSN:0008-4042    

DOI:10.1139/v67-097

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The effects of some changes of ambients on the dimensions of an activated carbon rod are presented. The emphasis is on the regions where anomalous contractions occur. It is suggested that dimensional changes can be used to estimate adsorption potentials of liquids of very low vapor pressures where adsorption isotherms cannot be measured by the usual methods.

ISSN:0008-4042    

DOI:10.1139/v67-098

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

By using the properties of hard-sphere systems as a point of departure, equations are derived for the residual properties of mixtures of real simple fluids at liquid-like densities. The essence of the derivation lies in a functional expansion ofg(r) expabout its hard-sphere value. The results obtained are useful for interpreting, correlating, and extending experimental data for both concentrated and dilute liquid solutions.

ISSN:0008-4042    

DOI:10.1139/v67-099

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A linear relationship between17O chemical shift and degree of π-bonding from oxygen to chromium in a number of chromium(VI) compounds is reported. The basis for this relationship is presented in terms of chemical shift theory. The17O chemical shift values for the two types of oxygen in the Cr2O72−ion are shown to be consistent with an angular rather than a linear Cr—O—Cr arrangement.

ISSN:0008-4042    

DOI:10.1139/v67-100

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The lattice parameter of La2Ce2O7fired at 1 400 °C was found to be 5.5700 ± 7 Å (at 20 ± 2 °C). Its crystal structure was of the disordered fluorite rather than the pyrochlore type. The degree of order in the structure could not be established from the neutron powder diffraction pattern, but it is likely that the metal and oxygen atoms were distributed at random, possibly with some tendency to short-range ordering. It would appear that for Ce4+the ionic size requirements for the formation of the pyrochlore structure are no longer satisfied, and that the cerates M23+Ce24+O7are outside the stability limits for 3–4 pyrochlores.

ISSN:0008-4042    

DOI:10.1139/v67-101

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Isotopic labelling techniques have been used to study the Co-60 γ-radiolysis of cyclohexane adsorbed at low coverage on silica gel. It has been shown that some of the energy absorbed in the silica gel is able to cause decomposition of the hydrocarbon, but it has also been shown that the silica gel takes part in the system as a chemical reactant. The effect on the radiolysis of changing the chemical nature of the gel by varying the water content was studied and it is shown that the radiolysis is quite different over gels with low and high water content. These changes are ascribed to the replacement of silanol groups by siloxane groups, with the removal of chemisorbed water.The effect of the additives N2O and SF6was studied in an attempt to determine how much of the reactivity was transferred from the solid by an ionic mechanism. It was concluded that over gels with a high water content more than one half of the reactivity was ionic in nature, whereas over gels with low water content much less was ionic.

ISSN:0008-4042    

DOI:10.1139/v67-102

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The kinetics of the hydrogen–ethylene reaction, catalyzed by unsupported copper, have been studied in the temperature range 0–250 °C. An empirical Rideal–Eley rate equation has been found to fit the data over the whole temperature range. A simplified Twigg mechanism is proposed to account for the experimental observations.

ISSN:0008-4042    

DOI:10.1139/v67-103

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Reactions of trapped (or solvated) electrons in solid ethanol have been studied. The following reactions occur at − 196 °C.The activation energy of reaction [6] is roughly 5 kcal/mole. Reaction [7] occurs with electrons that have not yet been trapped by the medium.Hydrogen atoms appear to be able to abstract from ethanol and to add to propylene at − 196 °C.

ISSN:0008-4042    

DOI:10.1139/v67-104

出版商:NRC Research Press    

年代:1967

数据来源: NRC