The adsorption and desorption of Cu on a smooth Pt electrode from 1 M H2SO4 solutions which contain a range of Cu2+ concentrations has been studied as a function of potential. The effect of adsorbed Cu on the oxidation rate of HCOOH has been examined at + 0.60 V (RHE). Cu2+ adsorption is controlled largely by an activation process. The slow step in the process is apparently the discharge of Cu2+ at the electrode to Cu+. Desorption of a preadsorbed Cu layer (+0.40 V) is extremely rapid at potentials+ 0.70 V, where no Cu2+ adsorption is normally found. Analysis of the oxidation state of the adsorbing layer by charge and coverage measurements yields a value of 1.92 electrons/site. This indicates that the major part of the layer is Cuads attached to a single Pt surface site. The rate of adsorption of Cu2+ is decreased slightly in the presence of 0.1 M HCOOH. At low coverages (θCuads⩽0.19), a slight enhancement of the HCOOH oxidation rate is observed at +0.60 V. Above this coverage, the oxidation process is inhibited. Results are interpreted in terms of Cu2+ adsorption mechanisms on Pt and the effect of the adsorbed layer on the mechanisms of HCOOH electro-oxidation on Pt.
本文研究了不同Cu2+浓度的H2SO4溶液对Cu在光滑Pt电极上的吸附和解吸过程。在+ 0.60 V (RHE)下，考察了吸附Cu对HCOOH氧化速率的影响。Cu2+吸附主要受活化过程控制。该过程的缓慢步骤显然是电极处的Cu2+向Cu+放电。在+ 0.70 V电势下，预吸附Cu层(+0.40 V)的脱附速度非常快，通常没有Cu2+吸附。通过电荷和覆盖率测量对吸附层的氧化状态进行分析，得出1.92个电子/位点的值。这表明该层的主要部分是附着在单个Pt表面的cuad。在0.1 M HCOOH的存在下，对Cu2+的吸附速率略有下降。在低覆盖率(θCuads≥0.19)下，在+0.60 V下观察到HCOOH氧化速率略有增强。在此覆盖范围以上，氧化过程被抑制。结果解释了Cu2+在Pt上的吸附机理，以及吸附层对HCOOH电氧化Pt机理的影响。
{"title":"Effect of adsorbed layers on the anodic oxidation of simple organic compounds. Part 3.—Cu adsorption on Pt and its effect on the oxidation of HCOOH","authors":"A. H. Taylor, S. Kirkland, S. Brummer","doi":"10.1039/TF9716700809","DOIUrl":"https://doi.org/10.1039/TF9716700809","url":null,"abstract":"The adsorption and desorption of Cu on a smooth Pt electrode from 1 M H2SO4 solutions which contain a range of Cu2+ concentrations has been studied as a function of potential. The effect of adsorbed Cu on the oxidation rate of HCOOH has been examined at + 0.60 V (RHE). Cu2+ adsorption is controlled largely by an activation process. The slow step in the process is apparently the discharge of Cu2+ at the electrode to Cu+. Desorption of a preadsorbed Cu layer (+0.40 V) is extremely rapid at potentials+ 0.70 V, where no Cu2+ adsorption is normally found. Analysis of the oxidation state of the adsorbing layer by charge and coverage measurements yields a value of 1.92 electrons/site. This indicates that the major part of the layer is Cuads attached to a single Pt surface site. The rate of adsorption of Cu2+ is decreased slightly in the presence of 0.1 M HCOOH. At low coverages (θCuads⩽0.19), a slight enhancement of the HCOOH oxidation rate is observed at +0.60 V. Above this coverage, the oxidation process is inhibited. Results are interpreted in terms of Cu2+ adsorption mechanisms on Pt and the effect of the adsorbed layer on the mechanisms of HCOOH electro-oxidation on Pt.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"809-818"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716700809","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57616462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P.m.r. measurements have been made on macroscopically-ordered samples of the smectic mesophase which occurs in the mono-octanoin + water system. The angular dependence of the doublet splittings obtained from both alkyl chain and hydroxyl protons indicate that there is a measurable degree of molecular ordering along a direction perpendicular to the lamellar planes of the mesophase. The degree of ordering of the alkyl chains is similar to that previously observed in magnetically-ordered nematic mesophases. The ordering of the water molecules is much smaller in magnitude and comparable to that previously observed in some hydrated silicates and fibrous materials.
{"title":"Investigation of lipid + water systems. Part 4.—Proton magnetic resonance in an ordered lyotropic mesophase","authors":"M. P. Mcdonald, W. Peel","doi":"10.1039/TF9716700890","DOIUrl":"https://doi.org/10.1039/TF9716700890","url":null,"abstract":"P.m.r. measurements have been made on macroscopically-ordered samples of the smectic mesophase which occurs in the mono-octanoin + water system. The angular dependence of the doublet splittings obtained from both alkyl chain and hydroxyl protons indicate that there is a measurable degree of molecular ordering along a direction perpendicular to the lamellar planes of the mesophase. The degree of ordering of the alkyl chains is similar to that previously observed in magnetically-ordered nematic mesophases. The ordering of the water molecules is much smaller in magnitude and comparable to that previously observed in some hydrated silicates and fibrous materials.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"890-896"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716700890","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57617082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An absorption spectrum in the range 200–220 nm, observed during the flash photolysis of Se2Br2, is attributed to SeBr. A vibrational analysis gives the following parameters of the states involved: X(2Πi): Te= 0 and 1070+a cm–1; ωe= 317 cm–1, ωexe= 0.7 cm–1, B: Te= 47 227 and 47 227+a cm–1; ωe= 393 cm–1, ωexe= 2.0 cm–1. An absorption spectrum due to TeI in the range 220–250 nm has been recorded in the flash photolysis of TeI2. The vibrational constants of the various states involved are: X(2Πi): Te= 0; ωe= 217 cm–1, ωexe= 0.6 cm–1. B: Te= 41 057 cm–1; ωe= 260 cm–1, ωexe= 1.4 cm–1. C: Te= 43 658 cm–1; ωe= 252 cm–1, ωexe= 0.5 cm–1.
{"title":"Ultra-violet spectra of SeBr and TeI","authors":"G. Oldershaw, K. Robinson","doi":"10.1039/TF9716700907","DOIUrl":"https://doi.org/10.1039/TF9716700907","url":null,"abstract":"An absorption spectrum in the range 200–220 nm, observed during the flash photolysis of Se2Br2, is attributed to SeBr. A vibrational analysis gives the following parameters of the states involved: X(2Πi): Te= 0 and 1070+a cm–1; ωe= 317 cm–1, ωexe= 0.7 cm–1, B: Te= 47 227 and 47 227+a cm–1; ωe= 393 cm–1, ωexe= 2.0 cm–1. An absorption spectrum due to TeI in the range 220–250 nm has been recorded in the flash photolysis of TeI2. The vibrational constants of the various states involved are: X(2Πi): Te= 0; ωe= 217 cm–1, ωexe= 0.6 cm–1. B: Te= 41 057 cm–1; ωe= 260 cm–1, ωexe= 1.4 cm–1. C: Te= 43 658 cm–1; ωe= 252 cm–1, ωexe= 0.5 cm–1.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"23 19 1","pages":"907-912"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716700907","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57617161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The absorption anisotropy of 1,2,4,5 tetramethylbenzene crystals in the region 33 000–40 500 cm–1 is investigated at room and liquid nitrogen temperature. The f-values for both directions of propagation of the light vector in the (001) face were measured and corrected for reflectivity losses. Frequency shifts of the absorption peaks and changes in f-values with temperature are discussed. Comparison of crystal absorption with oriented gas intensities leads to the conclusion that the transition is long-axis polarized. The assignment is discussed in relation to a calculation on crystal shift and Davydov splitting. The probable orientation and magnitude of the transition moment, induced by the crystal field in the unit cell, is indicated.
{"title":"Intensities in polarized light: near ultraviolet absorption spectrum of 1,2,4,5 tetramethylbenzene","authors":"A. Brillante, C. Zauli","doi":"10.1039/TF9716700913","DOIUrl":"https://doi.org/10.1039/TF9716700913","url":null,"abstract":"The absorption anisotropy of 1,2,4,5 tetramethylbenzene crystals in the region 33 000–40 500 cm–1 is investigated at room and liquid nitrogen temperature. The f-values for both directions of propagation of the light vector in the (001) face were measured and corrected for reflectivity losses. Frequency shifts of the absorption peaks and changes in f-values with temperature are discussed. Comparison of crystal absorption with oriented gas intensities leads to the conclusion that the transition is long-axis polarized. The assignment is discussed in relation to a calculation on crystal shift and Davydov splitting. The probable orientation and magnitude of the transition moment, induced by the crystal field in the unit cell, is indicated.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"913-921"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716700913","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57617171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Gal, O. Janković, S. Malčić, P. Radovanov, M. Todorović
Linde 4A zeolite was converted to Ni, Co, Zn and Cd forms by replacing sodium ions with divalent cations. The replacement was from 82%(Ni) up to 100%(Cd). Chemical, T.G.A., D.T.A. and X-ray analysis of the divalent metal zeolites have been made and data on the composition of the unit cells and the thermal stability of the lattices were obtained. Ni-zeolite is unstable, its crystal lattice being completely destroyed above 70°C, whereas Co-, Zn- and Cd-zeolites are stable up to 750–850°C. The adsorption of water on the latter zeolites is reversible. Ion-exchange isotherms for Co2+, Zn2+ and Cd2+ at three temperatures were obtained and the thermodynamic functions, ΔG°, ΔH° and ΔS°, of the ion-exchange equilibria calculated. The thermodynamic data are discussed with respect to hydration and size of the cations. A possible explanation of the instability of Ni-zeolite is suggested.
{"title":"Ion-exchange equilibria of synthetic 4A zeolite with Ni2+, Co2+, Cd2+ and Zn2+ ions","authors":"I. Gal, O. Janković, S. Malčić, P. Radovanov, M. Todorović","doi":"10.1039/TF9716700999","DOIUrl":"https://doi.org/10.1039/TF9716700999","url":null,"abstract":"Linde 4A zeolite was converted to Ni, Co, Zn and Cd forms by replacing sodium ions with divalent cations. The replacement was from 82%(Ni) up to 100%(Cd). Chemical, T.G.A., D.T.A. and X-ray analysis of the divalent metal zeolites have been made and data on the composition of the unit cells and the thermal stability of the lattices were obtained. Ni-zeolite is unstable, its crystal lattice being completely destroyed above 70°C, whereas Co-, Zn- and Cd-zeolites are stable up to 750–850°C. The adsorption of water on the latter zeolites is reversible. Ion-exchange isotherms for Co2+, Zn2+ and Cd2+ at three temperatures were obtained and the thermodynamic functions, ΔG°, ΔH° and ΔS°, of the ion-exchange equilibria calculated. The thermodynamic data are discussed with respect to hydration and size of the cations. A possible explanation of the instability of Ni-zeolite is suggested.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"999-1008"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716700999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57617242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A simple analysis of the degassing kinetics of metal wires is presented in order to examine the dependence of the rate of efflux of the dissolved gas on the physical and thermodynamic parameters of the system. In practice, the process often tends to be dominated either by the rate of diffusion of the gas within the metal, or by the desorption rate at the surface. There is, however, some indication that there are situations in which both factors may operate together.
{"title":"Degassing kinetics of metal wires","authors":"W. Lamb","doi":"10.1039/TF9716701137","DOIUrl":"https://doi.org/10.1039/TF9716701137","url":null,"abstract":"A simple analysis of the degassing kinetics of metal wires is presented in order to examine the dependence of the rate of efflux of the dissolved gas on the physical and thermodynamic parameters of the system. In practice, the process often tends to be dominated either by the rate of diffusion of the gas within the metal, or by the desorption rate at the surface. There is, however, some indication that there are situations in which both factors may operate together.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"1137-1142"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716701137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57617692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The anhydride resulting from the dehydration of manganous formate dihydrate is crystalline and its skeletal structure is distinct from the dihydrate. Under the proper conditions of temperature and water vapour pressure the freshly dehydrated anhydride rehydrates readily and completely to the dihydrate. Rehydration against time curves have been obtained for anhydrides prepared from the dihydrate which was in the form of individual single crystals, crystalline powder, ground powder and reactor-irradiated powder. The pressure, time and temperature dependences of the rehydration process have been determined. The extent of rehydration is described by a square-root dependence on time. This suggests that the rehydration is diffusion-controlled. The rate of rehydration increases markedly with pressure. Below a supersaturation ratio of approximately 10, rehydration does not occur; rather there is an appreciable sorption. The rate of sorption is diffusion-controlled with an energy of activation for diffusion of 12.0 kcal /mol. Isotherms have been determined for the sorbed water.
{"title":"Kinetics of rehydration of crystalline anhydrides. Manganous formate","authors":"R. Eckhardt, Peter M. Fichte, T. Flanagan","doi":"10.1039/TF9716701143","DOIUrl":"https://doi.org/10.1039/TF9716701143","url":null,"abstract":"The anhydride resulting from the dehydration of manganous formate dihydrate is crystalline and its skeletal structure is distinct from the dihydrate. Under the proper conditions of temperature and water vapour pressure the freshly dehydrated anhydride rehydrates readily and completely to the dihydrate. Rehydration against time curves have been obtained for anhydrides prepared from the dihydrate which was in the form of individual single crystals, crystalline powder, ground powder and reactor-irradiated powder. The pressure, time and temperature dependences of the rehydration process have been determined. The extent of rehydration is described by a square-root dependence on time. This suggests that the rehydration is diffusion-controlled. The rate of rehydration increases markedly with pressure. Below a supersaturation ratio of approximately 10, rehydration does not occur; rather there is an appreciable sorption. The rate of sorption is diffusion-controlled with an energy of activation for diffusion of 12.0 kcal /mol. Isotherms have been determined for the sorbed water.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"1143-1154"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716701143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57618060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The γ-radiolysis of eleven carboxylic acids at cryogenic temperatures has been examined by e.s.r. and matrix isolation techniques. Radical-anions RĊOOH– were identified in all the acids examined except cyclopropane carboxylic acid, and their reactions studied. The main features of the radiolysis may be interpreted by means of a mechanism similar to that proposed earlier for acetic acid.
{"title":"Electron spin resonance studies of fundamental processes in radiation- and photo-chemistry. Part 7.—The γ-radiolysis of carboxylic acids at cryogenic temperatures","authors":"P. Ayscough, J. Oversby","doi":"10.1039/TF9716701365","DOIUrl":"https://doi.org/10.1039/TF9716701365","url":null,"abstract":"The γ-radiolysis of eleven carboxylic acids at cryogenic temperatures has been examined by e.s.r. and matrix isolation techniques. Radical-anions RĊOOH– were identified in all the acids examined except cyclopropane carboxylic acid, and their reactions studied. The main features of the radiolysis may be interpreted by means of a mechanism similar to that proposed earlier for acetic acid.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"1365-1375"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716701365","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57619434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rate constants for the unimolecular elimination of HF from chemically-activated CH2FCH2F, produced in the photolysis of 1,3-difluoroacetone alone and in the presence of silanes, have been interpreted in terms of the RRKM theory of unimolecular reactions, and a critical energy of 63 kcal mol–1* obtained for the reaction. The rate constants are compared with previous data, and the dependence of the results on the thermochemistry of the system, and on the transition state model adopted are discussed.
{"title":"Application of the RRKM theory to the unimolecular decomposition of 1,2-difluoroethane","authors":"J. Kerr, D. Timlin","doi":"10.1039/TF9716701376","DOIUrl":"https://doi.org/10.1039/TF9716701376","url":null,"abstract":"The rate constants for the unimolecular elimination of HF from chemically-activated CH2FCH2F, produced in the photolysis of 1,3-difluoroacetone alone and in the presence of silanes, have been interpreted in terms of the RRKM theory of unimolecular reactions, and a critical energy of 63 kcal mol–1* obtained for the reaction. The rate constants are compared with previous data, and the dependence of the results on the thermochemistry of the system, and on the transition state model adopted are discussed.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"67 1","pages":"1376-1383"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716701376","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57619635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electrical conductance measurements have been made in the MCl + ZnCl2(M = Na, K, Cs) systems over the temperature range from the liquidus to 600°C. While the results show marked non-Arrhenius character they cannot be usefully correlated in terms of the Adam-Gibbs configurational entropy model for transport.
{"title":"Electrical conductances of some alkali chloride + zinc chloride melts","authors":"H. Bloom, I. Weeks","doi":"10.1039/TF9716701416","DOIUrl":"https://doi.org/10.1039/TF9716701416","url":null,"abstract":"Electrical conductance measurements have been made in the MCl + ZnCl2(M = Na, K, Cs) systems over the temperature range from the liquidus to 600°C. While the results show marked non-Arrhenius character they cannot be usefully correlated in terms of the Adam-Gibbs configurational entropy model for transport.","PeriodicalId":23290,"journal":{"name":"Transactions of The Faraday Society","volume":"89 1","pages":"1416-1419"},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/TF9716701416","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57620036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：