摘要:

A high-precision, mixing calorimeter is described for the direct measurement of the enthalpy of liquid mixing under constant pressure conditions. Tests of the calorimeter using the benzene – carbon tetrachloride system at 25 °C show a reaction between mercury and carbon tetrachloride which leads to systematically high values for the heat of mixing. Tests with then-hexane–cyclohexane system at 25 °C give a maximum enthalpy of mixing Δmh = 222.14 + 0.21 J/mole at 0.586 cyclohexane mole fraction.

ISSN:0008-4042    

DOI:10.1139/v68-142

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The decomposition of acetonedicarboxylic acid at various pH and in the presence of cobalt, nickel, copper, and zinc perchlorates as catalysts has been investigated. In addition the equilibrium constants for the formation of complexes between the metal ions and the acetonedicarboxylate ion have been measured.The copper complex appears to differ from the others in being more acidic, and also in its infrared spectrum. The kinetic results have been interpreted in terms of rate constants for the decomposition of each of the complexes, and a qualitative (but not a quantitative) correlation seems to exist between the rate constants and the stability constants of the complexes.

ISSN:0008-4042    

DOI:10.1139/v68-143

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reaction between mercury (3P1) atoms and dimethylsulfide at 55 °C has been shown to be exclusivelyTwo primary modes of dissociation have been established for the corresponding reaction with dimethyldisulfide.The former reaction accounts for ~20% of the primary decomposition at 55 °C. No reaction leading to H-atom removal was found for either compound.The subsequent reactions of CH3S and CH3SS radicals, chiefly combination and disproportionation, have been investigated briefly.

ISSN:0008-4042    

DOI:10.1139/v68-144

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The dielectric absorption at several microwave frequencies of liquid ethylbenzene, isopropylbenzene, and phenyltrimethylsilane at 15, 37.5, and 50 °C and cyclohexane solutions oft-butylbenzene and benzotrichloride at 15, 37.5, 45, and 50 °C has been examined. Benzotrichloride has also been studied in cyclohexane andp-xylene solution at 25 °C. Only molecular reorientation can be detected for benzotrichloride, whereas the remainder are all characterized by an absorption that may be analyzed into two relaxation times, one associated with molecular reorientation (τ1) and a shorter relaxation time (τ2) which appears to be attributable to an intermolecular process. The enthalpies of activation of the τ1process show the expected increase with increasing molecular size, while no temperature dependence is detectable for the shorter relaxation process.

ISSN:0008-4042    

DOI:10.1139/v68-145

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The dielectric absorption at four microwave frequencies of pure liquid benzene andp-cymene at 25 °C,p-xylene and mesitylene at 25, 40, 50, and 60 °C, and solutions of durene and hexamethylbenzene in mesitylene at 60 °C has been examined. All show measurable loss factors and apparent dipole moments of about 0.1 to 0.2 D. These moments are less in magnitude than those associated with the short relaxation time (τ2) process for the polar monoalkylbenzenes.o-xylene andm-xylene. Their relaxation times are too short for molecular reorientation and there is a rough correlation between the number of collisions/molecule s and the reciprocal relaxation time.

ISSN:0008-4042    

DOI:10.1139/v68-146

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Ultrasonic absorption and velocity have been measured in anhydrous N,N-dimethylformamide solutions of hydrogen chloride, over the frequency range 13 to 143 mc/s, and the concentration range 0.05 Mto 3.5 M. A large relaxation is observed and ascribed to the association of the acid. The rate constants for this reaction are obtained, and their variations with concentration are discussed. The association rate appears to be entirely diffusion controlled, and the corresponding "reaction distance" is large. This may be related to the very large effect on the sound velocity (and hence on the compressibility) that arises from the introduction of these ions.

ISSN:0008-4042    

DOI:10.1139/v68-147

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A number of compositionsand of related mixed phases were prepared and investigated. For the trivalent lanthanons from La to Lu, and for Y, the homogeneous A2Sn2O7phases were of the cubic pyrochlore type (space groupFd3m, No. 227). Their lattice parameters gave a very good linear relationship when plotted against the Templeton–Dauben radii of A3+. The applicability of other sets of ionic radii was also tested. The lower limit of ther(A3+):r(Sn4+) ratio for cubic pyrochlore stannates is about 1.19 (Ahrens radii), while the upper limit is at least 1.60. Attempts to extend the lower limit by preparing mixed Yb + Sc stannates were only partially successful. Bi2Sn2O7is not a cubic pyrochlore.The structures of Y2Sn2O7and Sm2Sn2O7were refined from X-ray powder data, and that of La2Sn2O7, from neutron powder data. The positional parameter of the majority oxygen atom,x(O2), has been found to increase with the size of A3+. The distortion of the SnO6octahedra in the pyrochlore structure thus decreases with increasingr(A3+).From a systematic study of the infrared spectra of the stannates it appears that it is the size of the Y3+ion rather than its chemistry (as distinct from the Ln3+ions) that determines its place among the 3–4 pyrochlores. No evidence of ferroelectricity was found in Pr, Er, and Lu stannates between room temperature and 4.2 °K.

ISSN:0008-4042    

DOI:10.1139/v68-148

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Studies on the electrochemical formation and reduction of surface oxide at platinum electrodes have been carried out with particular reference to polarization and hysteresis effects in these processes. Comparisons between the results of galvanostatic and potential sweep techniques have been made for three types of surfaces of platinum electrodes prepared by: (a) heating in hydrogen; (b) heating in a flame; and (c) electrolytically forming platinum black surfaces. The dependence of the quantity of reducible oxide formed under prior steady-state potentiostatic conditions has been related to potential and time of anodic polarization. Polarization effects in the reduction of the surface oxide have been evaluated in terms of the potential dependence of the pseudocapacitance maximum for the oxide reduction process, and a mechanism for the reduction is suggested. The relative slowness of the reduction process is important in regard to the question of the role of oxide in the kinetics of electrocatalytic oxidations at platinum anodes. Hysteresis effects in anodic formation and cathodic reduction of the oxide are discussed in terms of a totally irreversible phase transition involving the ad-layer.

ISSN:0008-4042    

DOI:10.1139/v68-149

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Solutions of various organic compounds were mixed with zinc oxide powder. The mixtures of these compounds with zinc oxide were prepared by evaporating the solvent. When the zinc oxide with any of the additives is heated at 300 °C, two e.s.r. lines withgfactors of 1.960 and 2.004, namedl1andl2, were observed. The intensities ofl1andl2come to their equilibrium values after several minutes of heating. The results show thatl1andl2are not from two independently existing species but from the two species R1and R2, whose concentrations are connected with each other by some competitive equilibrium reactions. It was not possible to estimate the two equilibrium constants separately, but their product was estimated to be less than 2.5 × 10−8. R1is concluded to be Zni+(interstitial), while R2may be Zn+or (ZnOv)−(2v−1), where v is an integer. The compounds which gave strongl2were naphthoquinones, naphthols, benzoquinone, hydroquinone, and anthraquinone, while the compounds which gave strongl1were benzoin, anthrone, pyrene, and naphthalene.

ISSN:0008-4042    

DOI:10.1139/v68-150

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Cinnamaldehydeanils reacted readily with [Rh(CO)2Cl]2under mild conditions to form Rh(CO)2ClL (2), where L is PhCH=CH—CH=NPh or PhCH=CH—CH=NTo (Ph = phenyl, To = p-tolyl). Under vigorous conditions RhCl(CO)L2(3) was isolated from this reaction. From the infrared and proton magnetic resonance spectra the ligands, L, appear only to coordinate through the nitrogen atom to the rhodium.Cinnamaldehyde reacted with Rh(CO)2Cl(p-toluidine) to give (2b) in good yield. Heating (2) in boiling benzene afforded (3) and Rh metal. Triphenylphosphine reacted with (2) or (3) to form RhCl(CO)(PPh3)2. The reaction of (3) with 1,5-cyclooctadiene gave (1,5-C8H12)RhClL, which was also prepared by reaction of (1,5-C8H12RhCl)2with L.Some electronegatively substituted acetylenes reacted with (3) to yield the stable acetylene complexes (RC≡CR)RhClL2(R = CF3, COOMe).

ISSN:0008-4042    

DOI:10.1139/v68-151

出版商:NRC Research Press    

年代:1968

数据来源: NRC