摘要:

Selenium isotope effects in the reduction of sodium selenite and of sodium selenate have been studied. Rate constant ratios for the76Se and82Se species have been determined for the reactions Seiv → Se0(1.017), Sevi → Seiv(1.018), and Se0 → Seiv(1.010) at room temperature. Theoretical predictions of the first two ratios, from the use of models in which the rate-controlling steps are assumed to be Se—O bond cleavages in SeO32−and SeO42−, respectively, lead to predictions in good agreement with experiment.

ISSN:0008-4042    

DOI:10.1139/v66-057

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Volumetric data for gaseous ammonia–acetylene mixtures have been analyzed to obtain second virial coefficients as a function of temperature and composition. From the pure-component virial coefficients of ammonia and acetylene, Kihara-potential parameters were obtained and these were used to calculate the physical contributions to the second cross virial coefficients,B12. The difference between the experimentalB12and that calculated from the physical contribution is attributed to chemical interaction, or complex formation, between the two molecules. Chemical equilibrium constants have been calculated, and ΔH0and ΔS0for complex formation were found to be −(2 210) cal/mole and −16.6 cal/mole °K respectively. These results indicate very weak hydrogen bond formation between the nitrogen atom in the ammonia and the hydrogen atom in acetylene.

ISSN:0008-4042    

DOI:10.1139/v66-058

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The rate of the reaction between potassium ferrocyanide and potassium persulfate has been measured over a range of conditions. The rate is dependent on the potassium ion concentration, and it is shown that this is explained if it is assumed that KFe(CN)63−and KS2O8−are the reacting species. The equilibrium constants governing the formation of these ion pairs were measured with a cation-sensitive glass electrode. Similar constants for the products KFeCCN6)2−and KSO4−, and also for KNO3, were measured. From these equilibrium constants, the true rate constants of the reaction can be obtained, and it is shown that these vary with ionic strength in the manner predicted by Brönsted's equation.

ISSN:0008-4042    

DOI:10.1139/v66-059

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The spectrum of RhCl3in fused LiCl–KCl at 440 °C is sufficiently different from that of RhCl63−to suggest the existence of some other species such as dimeric or polymeric bridge-complexes, or, less likely, tetrahedral RhCl4−. The spectra of RhCl3and K3Rh(NO2)6in fused NaNO3–KNO3at 300 °C indicate the occurrence of nitro coordination in both systems, probably completely in the latter case, but in competition with chloro coordination in the former. Addition of KCl to a solution of RhCl3in NaNO3–KNO3causes spectral changes which suggest that RhCl63−is the principal rhodium species present.

ISSN:0008-4042    

DOI:10.1139/v66-060

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Hydrogen selenide may be generated by the reaction of hydrogen gas with liquid selenium according to the reactionwhereThe equilibrium constantKof this reaction was measured by passing hydrogen over liquid selenium at controlled rates of flow over the temperature range 525–625 °C. The equilibrium ratio of hydrogen to hydrogen selenide was determined by gas analysis. Over the temperature range 525–625 °C, the equilibrium constant can be expressed by the equationThis expression leads to ΔH298° = 9 174 ± 107 cal mole−1, ΔF298° = 5 132 cal mole−1, and ΔS298° = 13.56 e.u. (entropy units) for the respective heat, free energy, and entropy of formation of hydrogen selenide from hydrogen and crystalline selenium.

ISSN:0008-4042    

DOI:10.1139/v66-061

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The triplet mercury photosensitization of spiropentane affords ethylene, allene, and methylenecyclobutane as major reaction products. This indicates an olefinic-type interaction with the quaternary C—C σ-bond of spiropentane, the cleavage of which results in a triplet state diradical. The initially formed diradical may undergo isomerization through ring cleavage or deactivation by collision. The open chain diradical then either decomposes unimolecularly into C2H4 + C3H4or on collisional relaxation isomerizes to methylenecyclobutane.The paraffinic-type interaction between Hg* and spiropentane which would lead to C—H bond scission appears to have minor significance.

ISSN:0008-4042    

DOI:10.1139/v66-062

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

We describe a novel technique for measuring the ranges of interaction in the radiolysis of hydrocarbon mixtures, e.g. the distance between donor and acceptor molecules in an energy transfer process. Thin layers, 20 to 1 000 Å thick, of solidc-C6D12sandwiched between other materials which activate or deactivate the hydrocarbon, are irradiated. The yields of D2and HD are measured as a function of the layer thickness. These yields change rapidly when the layer thickness is comparable with the range of the interaction.We find: (a) the activation ofc-C6D12byn-C6H14has a very short range consistent with an ionmolecule reaction between nearest neighbor molecules; (b) the deactivation by CCl4or benzene has a longer range (180 Å or more) consistent with the average separation of positive ions and electrons in an irradiated hydrocarbon; (c) the intermediates in the bimolecular reaction giving HD in layers of C6D12and C6H12have a short range (< 100 Å) and cannot be thermal hydrogen atoms.

ISSN:0008-4042    

DOI:10.1139/v66-063

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A vacancy model, originally developed for the description of diffusion in substitutional alloys, is modified for application to aqueous solutions, including those containing ionic species. The results obtained with this model are similar to those of two recently published methods for estimatingL-coefficients in dilute multicomponent liquid systems.Agreement with experimentalL-coefficients at relatively high concentrations can be improved for this model by assuming that the jump probability of a diffusing species is inversely proportional to the relative viscosity of the mixture. Good agreement is then found for some systems up to combined solute concentrations of 3 M.

ISSN:0008-4042    

DOI:10.1139/v66-064

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The partial molar volume of ions in water furnishes an indication, if not precise information, about the nature of ionic solvation (1–5). Accordingly, it was hoped that differences in this term and particularly the effect of temperatures on the differences in the apparent partial molar volume for a series of ions in light and heavy water would provide a basis for decisions on the nature of solvation of the benzenesulfonic ion. This ion is of considerable interest in the study of solvolysis, but very little is known about the characteristics of solvation.

ISSN:0008-4042    

DOI:10.1139/v66-065

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The formation of a 1:1 π-complex between ethylene and ruthenium(II) in aqueous hydrochloric acid solution is described. The kinetics of the reaction were examined over a range of temperatures and of concentrations of ruthenium(II), ethylene, hydrogen ion, and chloride ion. The results suggest that complex formation proceeds through a stepwise (SN1) mechanism in which the initial step involves the dissociation of a chlororuthenate(II) complex.

ISSN:0008-4042    

DOI:10.1139/v66-066

出版商:NRC Research Press    

年代:1966

数据来源: NRC