bluuebunny/crossref_metadata_2025 huggingface dataset:
The Potential Energy Relationships in Normal and Excited Acetaldehyde
Authors: Davis Thomas W. , Burton Milton
Published: January 2005

By a simple modification and extension of the system of potential energy hypersurfaces used to correlate the observations in the thermal and the photochemical decomposition of acetaldehyde it is shown that the following effects are explained: (1) the dependence on temperature and wave-length of relative probabilities of free-radical and ultimate molecule production in the primary photochemical act; (2) the disappearance of fluorescence at shorter wave-lengths or at higher temperatures; (3) the separate maxima for band and continuous absorption; (4) the high quantum yield reported at 3340A.
Internal Rotation and Dipole Moment in Succinonitrile
Authors: Lewis George L. , Smyth Charles P.
Published: January 2005

A new heterodyne-beat apparatus has been employed to determine the dipole moment of acetonitrile from —60° to +60° and that of succinonitrile from —90° to +90° in solution. By assuming each half of the succinonitrile molecule to have the same moment as the acetonitrile molecule, the observed moments have been used to calculate the height of the potential barrier which restricts rotation around the carbon-carbon single bond in succinonitrile and thereby causes the moment of the molecule to increase with rising temperature. The value 1.2±0.5 kcal. thus obtained is in better agreement with the value 1.5 obtained from the calculation of the sum of the various potential energies existing between the two halves of the molecule than is warranted by the necessarily approximate nature of the calculation.
A Contribution to the Theory of Viscous Flow Reactions for Chain-Like Molecular Substances
Authors: Eirich F. , Simha R.
Published: January 2005

Ewell and Eyring investigated a relation for the coefficient of internal friction as a reciprocal reaction rate employing a large number of data. In this paper these investigations are extended to new data involving homologous series of higher esters. The variation of the activation heats of the flow process with temperature, molecular weight, and constitution, is considered and an attempt made to correlate it to the molecular constitution. There are indications that the above-mentioned ideas contain implicitly through Stefan's theorem a relation between surface tension and viscosity.
X-Ray Study of Benzene-Cyclohexane Mixtures
Authors: Murray G. E. , Warren B. E.
Published: January 2005

X-ray diffraction patterns have been made of benzene, cyclohexane, and three mixtures. The first strong peak of the mixtures is a single peak showing no trace of resolution into a benzene peak and a cyclohexane peak. If benzene-cyclohexane mixtures have an emulsion type of structure, such as postulated by H. K. Ward, the separation of the benzene and cyclohexane peaks is too small, relative to the peak widths, to allow the two component peaks to be distinguished. X-ray studies of benzene-cyclohexane mixtures can neither prove nor disprove the existence of an emulsion type of structure in the mixture.
Van der Waals' Forces and the Vapor Pressures of Ortho- and Parahydrogen and Ortho- and Paradeuterium
Authors: Cohen Karl , Urey Harold C.
Published: January 2005

The nonexchange interaction energies of pairs of orthohydrogen and of parahydrogen molecules are examined in detail. The first-order contribution is seen to contribute the specific heat anomaly of o-hydrogen at low temperatures. The second-order interaction is computed for cases where the first-order contribution is zero. Its contribution, calculated with explicit recognition of the influence of rotational energy on the electronic states, is shown to be of the correct sign and order of magnitude to account for the vapor pressure and volume differences of o- and p-hydrogen and deuterium. More exact confirmation cannot be obtained because of the approximations and the disturbing influence of the anharmonic zero-point vibrations.
The Thermodynamic Functions of Cyanogen and the Cyanogen Halides
Authors: Stevenson D. P.
Published: January 2005

The free energy function, heat content and heat capacity of cyanogen and the cyanogen halides, ClCN, BrCN and ICN, have been calculated for a series of temperatures from spectroscopic and electron diffraction data. Since no experimental value for the carbon-iodine distance has been as yet obtained, an extrapolation is made from the values for the carbon-chlorine and carbon-bromine distances in the corresponding cyanogen compounds. 1.96±0.04A is obtained for the I–C distance in cyanogen iodide. The free energies of formation of gaseous (CN)2, ClCN and ICN have been calculated from thermal and equilibrium data. The values of ΔF°298.1 are, 69.1 kcal./mole for (CN)2, 35.5 kcal./mole for ClCN, and 46.75 kcal./mole for ICN. It is estimated that for gaseous BrCN ΔF°298.1=40 kcal./mole.
Film Potentials of Stearate Multilayers and Other Dielectrics on Metal Surfaces
Authors: Harkins William D. , Mattoon Richard W.
Published: January 2005

A considerable amount of evidence is presented for the view that a part, if not all, of the film potential of an X multilayer of calcium stearate on a subphase of metal is due to a surface charge on the dielectric and a resultant induced charge in the metal. With a Y multilayer of an even number of layers, the potential, and therefore presumably the charge, is practically zero. This may indicate that the surface of the multilayer becomes charged only when it moves through the surface of the solution without the deposition of a new layer. There is some experimental evidence that the charge is less when the X multilayer moves upward through the monolayer of calcium stearate under no pressure than when it moves upward with the monolayer under pressure. The potential cannot be due to an equal charge deposited on and retained by every layer, since this indicates a film potential ΔV=4πnetN(N+1)/2ε increasing nearly as the square of the number of layers. The experiments indicate when X layers are deposited directly on the metal a variation as the first power, or ΔV=4πneNt/ε, which suggests a charge on the outer surface only. While Porter and Wyman find that if X layers are deposited upon a subphase of (X+Y) layers, the second X layer gives a very much smaller potential increment than the first (increments of 2.7, 0.06, 0.8, 0.8, 0.7, 0.35 and 0.35 volt), we obtain a much more constant value on stearic acid (0.248, 0.300, 0.271, 0.259) and on paraffin (0.769, 0.911, 0.900, 1.085 and 1.085, also on thicker paraffin 5.0 volts for the first and 6.0 volts for the second X layer). The above results do not agree with equations developed for either a constant charge on the outer X layer only, or upon every X layer. The film potential is found to be a function of the pH, and of the nature of the positive ions, of the subsolution. Experiments on the effects of α- and γ-rays are described. In general we have found that the potential relations of multilayers are much more complicated than is indicated by the work of others, but this is due to the fact that the conditions of deposition have been varied to a greater extent. The effect of electrolysis upon the contact potential of gold and the film potential of paraffin on gold, has been investigated. These phenomena are also complicated, so only a few of the results with aluminum chloride as the solute, are described.
Infra-Red and Raman Spectra of Polyatomic Molecules VI. Triborine Triamine, B3N3H6
Authors: Crawford Bryce L. , Edsall John T.
Published: January 2005

The Raman spectrum of liquid triborine triamine has been studied, and the infra-red absorption of the gas measured from 2.5 to 24.5μ. The molecule is assumed to be isoelectronic with benzene, belonging to the point group D3h, and an assignment of fundamental frequencies is given, based upon this structure. A normal coördinate treatment has been made, and used to calculate the three inactive frequencies and the isotope shifts due to the B10 isotope. The agreement between calculated and observed values is satisfactory except for the nonplanar frequencies, where strong interactions between bonds attached to the aromatic ring in metapositions are indicated. The fundamental frequencies of triborine triamine are compared with those of benzene; satisfactory correlation is obtained with the benzene frequencies given by Lord and Andrews. The frequencies of the triborine triamine are used together with structural data to calculate the thermodynamic properties of the substance.
An Absorption Band of Formaldoxime at λ9572
Authors: Zumwalt Lloyd R. , Badger Richard M.
Published: January 2005

The third harmonic of the O – H band in formaldoxime vapor has been found to lie at λ9572 (10,444.1 cm—1) and under high dispersion has been resolved and found to resemble a parallel band of a symmetric rotator. Owing to the weakness of the lines near the center of the band a definitely unique rotational analysis could not be made but the harmonic mean of the two larger moments of inertia appears to lie between the limits 73.3 and 76.6×10—40 g cm2. The hydroxyl hydrogen does not rotate freely and indeed its torsional oscillation appears not to have a very low frequency. It is not possible to locate this hydrogen uniquely until other parameters of the molecule have been determined by electron diffraction. The possible effect of resonance on the O – H frequency is discussed.
``Surface Elasticity'' of Protein Films. I. Egg Albumin
Authors: Bateman J. B. , Chambers Leslie A.
Published: January 2005

The limiting area is the quantity by which protein films are usually described. This may give some indication of the ``spreading tendency'' of the protein, but it is not necessarily related to other mechanical properties of the film, since an unknown proportion of the protein may remain unspread, or may pass into solution in the substrate. This is demonstrated by an experimental study of the limiting areas and the surface elasticities, MS = — A · dF/dA, of egg albumin films as a function of pH. It is shown that the MS — F curves for this protein are of characteristic form, with a single well-defined maximum, (MS)max. It is shown further that the characteristic large variations of limiting area with pH are not reflected in the variation of (MS)max and it is concluded that throughout the range of H ion concentrations studied the observed elasticities are due to a monomolecular film of true limiting area ∼1.0 m2/mg. The lower values of the apparent limiting area obtained at certain hydrogen ion concentrations are due principally to unspread material which does not contribute significantly to the mechanical properties of the film. It is suggested that the MS — F curves should be employed in place of the apparent limiting areas in the description of protein films and that the values of (MS)max may provide a convenient means of showing specific differences between films of different proteins.
Absolute Values of the Velocity Constants in the Formation of Semiquinone
Authors: Kornfeld G.
Published: January 2005

A mechanism for the autoxidation of hydroquinone and its homologs was presented in a previous paper. From this mechanism it is now possible to calculate a lower limit for the absolute velocity constant of the formation of semiquinone ions from quinone and doubly charged hydroquinone ions, and an estimate of this constant can be given in the analogous case of Ψ-cumohydroquinone. In both cases, the velocity constant is found to be remarkably high; under special experimental conditions the velocity of this reaction should become of the same order of magnitude as the velocity of the recombination of the doubly charged hydroquinone ions with hydrogen ions, thus providing a test for this latter velocity.
Gaseous Heat Capacities I. The Method and the Heat Capacities of C2H6 and C2D6
Authors: Kistiakowsky G. B. , Rice W. W.
Published: January 2005

An apparatus is described for the adiabatic expansion method of Lummer and Pringsheim, new features of which are a device for accurate and rapid pressure measurements and an effective design of the expansion vessel. The Wollaston wires, serving as a resistance thermometer, are subjected to extensive heat treatment which stabilizes their electrical characteristics so well that resistance changes accompanying gas expansion can be translated into temperature changes by means of separately determined temperature coefficients of resistance. The method here described is thus an absolute one and is not dependent on comparison with other gases of known heat capacity. Causes of imperfect temperature constancy after expansion are quantitatively discussed and traced to two processes: the heat conduction by the gas and the absorption of thermal radiation from the walls by the gas. Experimental data on air and carbon dioxide are presented and are compared with the theoretical values. Heat capacities of C2H6 and C2D6 are reported for the interval 0 to 90°C.
Infra-Red and Raman Spectra of Polyatomic Molecules. VIII. Dimethyl Ether
Authors: Crawford Bryce L. , Joyce Lois
Published: January 2005

The infra-red spectrum of dimethyl ether has been studied from 2.5 to 22.5μ, and the available Raman data correlated with it. A tentative vibrational analysis is given.
The Transference Numbers of Sodium Acetate in Aqueous Solution
Authors: LeRoy D. J. , Gordon A. R.
Published: January 2005

The transference numbers for sodium acetate in aqueous solution at 25°C for the concentration range 0.02N—0.17N have been determined by the same method as was used for potassium acetate. The results are in close but not exact agreement with those previously reported by Longsworth. The Longsworth function t+0′ is linear in the concentration only up to 0.1N.
The Thermal Decomposition of Methylene Diacetate, Ethylidene Diacetate and Paracetaldehyde at Low Pressures
Authors: Dacey J. R. , Coffin C. C.
Published: January 2005

By means of an optical lever manometer the decomposition velocities of methylene diacetate, ethylidene diacetate and paracetaldehyde have been measured down to pressures of 0.05 mm of mercury. No falling off in reaction rate has been observed. The minimum numbers of internal degrees of freedom contributing to the activation energies are thus 16, 18 and 64, respectively.
Density of Single Crystals of Cupric Acetate Monohydrate
Authors: Sidhu S. S. , Berger J. A.
Published: January 2005

Densities of single crystals of cupric acetate monohydrate have been determined by the pycnometer method for temperatures 21.0°C, 23.5°C and 25.0°C, and are 1.907±0.001, 1.891±0.004 and 1.880±0.003 g cm-3, respectively. The first one compares favorably with the value (1.906 g cm-3) calculated at about 21.0°C from accurately determined lattice parameters of the unit cell and the number of molecules per unit cell. It is considerably higher, however, than the value (1.882 g cm-3) given in the International Critical Tables.
Intensities of Electronic Transitions in Molecular Spectra V. Benzene
Authors: Mulliken Robert S.
Published: January 2005

The spectrum of benzene is discussed. According to the calculations, the strong N→V absorption region near and just below λ2000 should be stronger than for a molecule with three unconjugated double bonds. New quantitative measurements on the spectrum near and below λ2000 would be of interest. Relations of the spectra of pyridine and of benzene derivatives to that of benzene are briefly discussed.
Intensities of Electronic Transitions in Molecular Spectra VI. Molecular Refractivities of Organic Compounds
Authors: Mulliken Robert S.
Published: January 2005

In connection with intensity calculations on the spectra of dienes and other compounds in III, IV and V of this series, a study is made of molecular refractivities. Rough theoretical calculations are made on the partial refractivities for the unsaturation electrons in open-chain and cyclic dienes (particularly conjugated dienes) and in benzene. The observed exaltations of the refractivity and dispersion in open-chain conjugated dienes appear to be satisfactorily explained qualitatively, and to a certain extent semi-quantitatively, by the rough calculations. Exaltations in other conjugated systems (e.g. systems with conjugated triple bonds, or with conjugation of C=O and C=C bonds) can be explained along similar lines. The refractivity data on unconjugated alkenes and dienes and on the conjugated cyclic dienes appear also to be in harmony with the theory. The considerable effects of alkyl substitution on the exaltation in substituted butadienes, benzenes, and styrols are attributed to hyperconjugation. Saturated compounds are briefly discussed in Section 4.
Depolarization Measurements on Raman Lines by an Easy, Accurate Method
Authors: Cleveland Forrest F. , Murray M. J.
Published: January 2005

The depolarization factors of Raman lines are determined by a method in which a Polaroid disk, so oriented that it passes light whose electric vector is horizontal, is placed between the Raman tube and the lens which condenses the scattered light on the slit of the spectrograph. Two exposures of equal duration are made, one with the arc below, the other with it at the side, of the horizontal Raman tube. The ratio of the intensities in the two exposures (depolarization factor) is determined by comparison with the lines of seven argon spectra produced by argon light of known intensity ratios. Important advantages of the method are the comparatively short exposure times and the elimination of errors due to the polarization characteristics of the spectrograph. Results for the depolarization factors of Raman lines obtained from a mixture of benzene and carbon tetrachloride are given and comparison with previous data for these compounds is made.
Studies on Aging and Formation of Precipitates XXIX. The Thermal Aging and Abnormal Physical Properties of Fresh Silver Bromide
Authors: Kolthoff I. M. , O'Brien A. S.
Published: January 2005

(1). Freshly precipitated silver bromide has a large surface development and is subject to thermal aging at room temperature in the air-dried state. During the aging the magnitude of the surface decreases and also the speed of incorporation of radioactive bromide, when bromine dissolved in ethyl bromide or in a gas phase is shaken with the solid. (2). A rapid exchange occurs between bromide in fresh air-dried silver bromide and radioactive bromine dissolved in ethyl bromide or bromine in the gas phase. (3). Fresh silver bromide has a relatively large electrical conductivity which is at least partly ionic.
The Thermal Chlorination of Chloroform
Authors: Taylor H. Austin , Hanson William E.
Published: January 2005

The thermal chlorination of chloroform has been studied in the range 260–320°C, using chloroform to chlorine ratios from 10 down to ⅙. For high partial pressures of chloroform the reaction is independent of the chloroform and unimolecular with respect to chlorine. At lower chloroform pressures there is a small dependence on the chloroform in addition to the first-order dependence on chlorine. A mechanism similar to one postulated for the photochemical chlorination of chloroform is discussed and a comparison with the thermal hydrogen-chlorine mechanism leads to the significant conclusion that the reaction has a chain mechanism initiated by chlorine atoms originating on the walls. Production of the latter is interfered with by chloroform adsorption and possibly also by adsorption of reaction products. The chains are broken principally in the gas phase.
Vibration-Rotation Bands of Some Polyatomic Molecules in the Photographic Infra-Red
Authors: Thompson H. W.
Published: January 2005

The infra-red absorption of methyl mercaptan, α-methyl hydroxylamine, methyl nitrite, methyl formate, dimethyl ether, formamide, methyl fluoride, methyl chloride, methyl bromide and methyl iodide has been measured over the range 7000–12,000A using low dispersion. The intense bands have been reexamined using higher dispersion. An analysis has been made of some bands in the spectra of the methyl halides. A parallel band of methyl fluoride suggests a moment of inertia of 33.7×10—40 g cm2. The spacing between the Q branches in perpendicular type bands appears to be irregular, and other peculiarities are noticed which indicate that the simple theory may need modification.
Kinetics of OH Radicals as Determined by Their Absorption Spectrum1 V. A Spectroscopic Determination of a Rate Constant
Authors: Oldenberg O. , Rieke F. F.
Published: January 2005

In order to determine the efficiency with which triple collisions bring about the recombination of free OH radicals, the rate constant for the reaction must be known in absolute units. Consequently it is necessary to measure in absolute units the ``standard concentration'' on which is based the rate constant previously determined spectroscopically by Frost and Oldenberg. For this purpose the intensities of the OH absorption lines in their ``standard discharge'' were measured and combined with the f values recently published. Because of the very small width of the OH absorption lines in the discharge, Fabry-Pérot plates had to be used in order to produce absorption spectra with a resolution sufficiently high for suitable intensity measurements. It was found that the efficiency of triple collisions is higher than unity if the number of such collisions is computed from gas kinetic data. This result indicates that OH forms collision complexes which have a lifetime much greater than the duration of bimolecular collisions between stable molecules.
Electrical Properties of Multilayers
Authors: Goranson R. W. , Zisman W. A.
Published: January 2005

This paper presents certain results on the electrical properties of multilayers of stearic acid and various stearates plated on insulating materials. The experimental data lead to the conclusion that the electrical charges of these multilayers arise from the adsorption of ions from the substrate on the carboxyl groups of the floating stearate monolayer. With a calcium-bearing substrate, for example, the first stage in the process is a conversion of stearic acid to calcium stearate and this reaction is a function of the substrate pH and consequently of the degree of ionization of stearic acid. The next stage is represented by an adsorption of calcium ions on the carboxyl groups of the calcium stearate which are carried along with the monolayer in the plating process. The electric charges of X-multilayers thus arise from volume distributions of positive adsorbed ions. The positive ions adsorbed on the floating monolayer induce a cloud of negative ions in their neighborhood which, under certain conditions such as dependence on size and valency of the negative ions, may lead to electrically neutral and wetted films. With certain types of mixed films, i.e., where the percentage of stearic acid present is appreciable, the rate at which the plating process is carried out becomes an important factor in determining whether X- or Y-type films can be built up, and for these cases fast dipping and withdrawal speeds can neutralize an existing multilayer charge. In plating X-multilayers it has been observed that after about 500 layers have been deposited, and the electrostatic repulsive field of the multilayer has thus reached a certain value, the upper portion of the submerged probe has a silvery appearance which gradually moves down the probe with increasing number of dips, and film does not adhere to the multilayer over this portion. This electrostatic repulsive field thus sets a limit to the thickness of X-multilayers on insulators. Under certain conditions the outer layer of multilayers dipped in film-free solutions overturns and adsorbs ions from the solution, resulting, in some cases, in wetted films and, in others, in an electrical charging of the multilayers.
The Skeletal Modes of Vibration of Long Chain Molecules
Authors: Kirkwood John G.
Published: January 2005

The method of Born, Karman and Blackman, designed for the determination of the normal modes of crystals, offers interesting possibilities in the case of certain polyatomic molecules possessing structural periodicity. The applicability of the method as a means of approximating the skeletal frequencies of the normal paraffin hydrocarbons is investigated. Although the calculations are not carried beyond the qualitative stage, they provide rather illuminating results.
A Simple Theory for Separation of Gases by Thermal Diffusion
Authors: Gillespie L. J.
Published: January 2005

Equations are derived in a simple manner by equating the net bombardment of each species across a plane between two adjacent thin layers of the gas mixture to the amount of each species returned across the plane by a return flow, which flow is assumed necessary to keep the pressure constant and is assumed to carry back the various species in the proportions in which they exist in the neighborhood. The average temperatures of the layers differ by dT, but the bombardment of each species is assumed independent and calculable in any layer in the way the pressure of an ideal gas at constant temperature is calculated. The resulting equation for binary mixtures does better than give the order of magnitude of the observed separations. It appears to give an upper limit, either in agreement with data or somewhat higher—up to about twice the observed value—and to fit data somewhat better than does the approximate equation of Chapman. The agreement is poorest for mixtures containing hydrogen and also whenever the lower temperature is extremely low. The equations for mixtures of any number of species are simple. They indicate that the separation of two heavier species should be improved by addition of a light gas. An attempt to improve the equations by introduction of mean free paths is found profitless, unless arbitrary values are to be chosen.
Intensities of Electronic Transitions in Molecular Spectra VIIIa. Odd-Numbered Conjugated Polyene Chain Molecules and Organic Dyes (with notes on optical anisotropy and Raman intensities)
Authors: Mulliken Robert S.
Published: January 2005

Using the Hückel LCAO molecular orbital approximation, it is found that the lowest excited electronic levels, long wave-length electronic spectra, and so on, should show exactly the same special features for conjugated polyene chain molecules with an odd as for those with an even number of atoms in the conjugated chain. Examples of even-numbered conjugated chain molecules are the carotenoids, discussed previously. Many dye molecules (for example, certain infra-red sensitizers) are salts whose positive ion is built on an odd-numbered conjugated chain with a nitrogen atom terminating the chain at each end. It seems probable that the explanation of the spectra of these dyes is essentially similar to that of the carotenoids, although much remains to be done toward understanding the effect of phenyl and other unsaturated groups when included in the conjugated chains. Absorption and refraction of carotenoid crystals are briefly discussed; the predicted strong pleochroism and double refraction are known experimentally. Bearing of the papers of the present series on Raman intensities of conjugated chain molecules is briefly discussed. A correction is given of an error in papers VI and VII of this series.
Remarks on the Calculation of Bond Strength in Methane
Authors: Taylor H. Austin , Burton Milton
Published: January 2005

A recomputation has been made of the C–H bond strength in CH4 by the method of Voge, using more recent data. The premises on which the calculations are based have been examined and it is concluded that the recalculated value (∼103 kcal.) is in good agreement with the value of 94.8 kcal. given by Burton when the approximations used in the Voge method are taken into account.
Reactions Involving Hydrogen and the Hydrocarbons
Authors: Gorin Everett , Kauzmann Walter , Walter John , Eyring Henry
Published: January 2005

The activation energies of the reactions H+CH4=CH3+H2 (1) and D+CH4=CH3D+H (2) have been calculated by using the semi-empirical method in combination with the treatment of directed valence used by Van Vleck and Voge. The activation energies for reactions (1) and (2) were found to be 9.5 kcal. and 37 kcal. This result agrees with the prediction of 40 kcal. of Rice and Teller for reaction (2). In addition it is found that the energy surface corresponding to the reaction H+CH4 contains a basin 8 kcal. deep corresponding to a stable CH3–H–H molecule. The rapid recombination of H atoms in the presence of methane, observed by Farkas and Melville is interpreted in terms of this CH3–H–H intermediate. The experimental data on the reactions of hydrogen and deuterium atoms with hydrocarbons have been reinterpreted in terms of atom-cracking reactions of the type D+C2H5→C2H5D→CH3D+CH3.
Some Remarks on the Theory of Reaction Rates
Authors: Wigner Eugene P.
Published: January 2005

Effects connected with a more complicated nature of the energy surfaces of relatively simple reactions are discussed. The theory of elementary association reactions is examined and it is shown that better results are obtained in the rate of association of atoms when three additional attraction states are taken into consideration. The rates of association of iodine, bromine and chlorine atoms are calculated and compared with the experimental rates. The improvement to be expected from consideration of the angular momentum of the associating pair of atoms is discussed.
On Intramolecular Diffusion, Quantum Theory, and the Calculation of Unimolecular Velocity-Constants
Authors: Christiansen J. A.
Published: January 2005

The internal rearrangement of molecules can be considered as the diffusion from one part of a potential energy surface to another. It is suggested that the ordinary diffusion equations might be applied to these cases. The viewpoint is alternative to the method of the activated state. An attempt is made to place this approach on a quantitative basis and to treat it with the help of quantum theory.
The Nature of the Critical Complex and the Effect of Changing Medium on the Rate of Reaction
Authors: Scatchard George
Published: January 2005

The nature of a critical complex may often be related to the change of the rate of the corresponding reaction when the solvent medium is varied by altering either the electrolyte concentration or the dielectric constant. It is necessary to take into consideration the ratio of volume concentration to mole fraction, the possibility of catalytic action, even that due to an ionic charge, and the possibility that the nature of the critical complex may change with changing composition. The critical complex of the bromoacetate-thiosulfate reaction appears to be the two tangent ions. In the ammonium-cyanate reaction there may be a partial de-polarization of the tangent ions. The effect of changing dielectric constant on the solvolysis of tertiary butyl chloride indicates a rather wide separation of the ions in the critical complex.
On the Rate of Ionization in Aqueous Solution of the Carbon-Hydrogen Bond in Aliphatic Compounds
Authors: Bonhoeffer K. F. , Geib K. H. , Reitz O.
Published: January 2005

The rate at which the carbon-hydrogen bond ionizes to give protons is studied by exchange with deuterium oxide. A base catalyst such as OD- ion is used. A large number of data are correlated in terms of the rate constants k at 25°. In some cases the calculations required to bring the data to comparable conditions are only approximate. The data are restricted to aliphatic compounds and include measurements on nitrohydrocarbons, acetone, acetaldehyde, acetic acid, acetonitrile, methyl sulfonic acid, halogenated compounds and hydroxl compounds. The velocity constants of ionization range from 103 to 10-7, and the order in which the various substituents affect the rate of the CH ionization is given. The influence of substitution on the ionization constants of carboxylic acids has long been studied from the standpoint of thermodynamics. The ionization of CH is a simpler process than the ionization of COOH and it should be possible to learn more of the mechanism through kinetics.
The Explosion of Ethyl Azide in the Presence of Diethyl Ether
Authors: Rice O. K. , Campbell Hallock C.
Published: January 2005

In this paper explosion limits and induction periods for the explosion of ethyl azide in the presence of diethyl ether are reported and compared with data for pure ethyl azide. From the explosion limits certain deductions are made regarding the rate of loss of heat from the reaction flask. From the induction periods calculations of the heat of reaction are made. These give fairly consistent results over the range of temperatures, pressures, and compositions used, and are believed to offer further support to the contention that the explosion of ethyl azide is a thermal explosion. The heat of reaction found seems to be consistent with thermochemical data on related compounds. The method of calculation of the heat of reaction is applied to data of Appin, Chariton, and Todes on methyl nitrate. In this case the heat of reaction found from the explosion is inconsistent with thermochemical data, and it is concluded that the explosion of methyl nitrate cannot be a thermal explosion.
Mechanisms of Complex Reactions and the Association of H and O2
Authors: von Elbe Guenther , Lewis Bernard
Published: January 2005

The kinetics of the upper explosion limit and the nonexplosive thermal reaction of H2 and O2 uniquely demonstrates the formation of HO2 in collisions H+O2+M, its destruction on surfaces and its ability to propagate chains by gas phase reactions with H2. Below 500° HO2 gradually ceases to be a chain carrier in the gas phase; assuming its further reactions to be heterogeneous, involving self-neutralization and reaction with H2, the kinetics of the mercury-photosensitized H2–O2 reaction are well interpreted. Bates' mechanism for this latter reaction, in which HO2 is postulated to react in the gas phase, is shown to be inconsistent with the thermal reaction. Data on the oxygen-inhibited photosynthesis of HCl and on the H concentration in the mercury-photosensitized H2–O2 reaction indicate that a fraction of the associations of H and O2 occurs in binary collisions. A quantum-mechanical treatment by Rosen shows that this process is possible. The partially binary character of the association is consistent with data on the photo-oxidation of HI. The reactions of HO2 in a mixture of H2, Cl2, O2 and HCl are discussed. Recent confirmation of the reaction HCO+O2=HO2+CO greatly strengthens the proposed mechanism of the oxidation of aldehydes and hydrocarbons. The rate coefficient of the reaction H+O2+H2=HO2+H2 is found to be 0.81×1013 cm6 mole—2 sec.—1 at room temperature. With O2 as a third body the rate coefficient is about ⅓, and with N2 about ½ of this value. The rate coefficient of the reaction H+O2=HO2 is found to be 0.74×108 cm3 mole—1 sec.—1 at room temperature. Comparison of the above value of the rate coefficient of H+O2+H2 with that estimated from data on the upper explosion limit shows that this reaction probably has no positive temperature coefficient, while a negative temperature coefficient is not ruled out.
The Polymerization of Gaseous Butadiene
Authors: Kistiakowsky G. B. , Ransom W. W.
Published: January 2005

Dimerization of butadiene has been studied in the temperature range from 446 to 660°K. The rate constant is expressed approximately by the equation: k2=9.20·109 exp (−23,690/RT) cc mole−1sec.−1.Deviations from this relation suggest an increase of activation energy with temperature. 3-vinyl cyclohexene formed in the dimerization reaction undergoes further addition with butadiene to give Δ3,3′-octahydro diphenyl. The rate constant of this reaction is given by the equation: k3=1.3·1014 exp (−38,000/RT) cc mole−1sec.−1,but the data on which it is based are not very accurate. Statistical calculation of the entropy of an activated complex which has the resonating structure H2C lim ⋮...−CH...−C lim ⋮H–CH2–CH2–C lim ⋮H...−CH...−C lim ⋮H2gives agreement with experimental data to within a factor of ten whereas the assumption that the reaction goes in a single step to the cyclic product gives a rate differing by more than a thousand-fold from the observed one. The role of resonating free radicals in other reactions of the dienes is discussed briefly.
The Experimental Basis for the Theory of Quasi-Unimolecular Reactions
Authors: Pease Robert N.
Published: January 2005

Reactions which have been represented as of the quasi-unimolecular type are reviewed. With the possible exception of the isomerization of cyclopropane to propylene, it is suggested that no clean-cut examples have so far been discovered. In view of this conclusion it is further suggested that the apparent restriction placed on rate of activation by collision is in need of review.
The Decomposition of Ethyl Bromide and the Collision Theory of First-Order Reactions
Authors: Daniels Farrington , Veltman Preston L.
Published: January 2005

The reaction C2H5Br→C2H4+HBr has been studied in the neighborhood of 400° with special reference to the effect of the wall surface and the addition of bromine. Earlier experimental facts are summarized and shown to be in agreement with the hypothesis that the primary step is the production of C2H5 and Br, followed by chemical reactions which do not involve a long chain. The low pressure effects are explained on the basis of wall effects. The decrease in the value of the first-order rate constant at low pressures can be explained in this reaction and in the decomposition of nitrogen pentoxide without the aid of the collision theory. It is suggested that other examples which have been regarded as confirmations of the collision theory may find similar explanations. It may be necessary to revise the quantitative aspects of the collision theory to allow for a decrease in k at lower pressures than have been heretofore considered.
Fluorescence and Photochemical Kinetics of Polyatomic Molecules in the Gas Phase
Authors: Noyes W. Albert , Henriques F. C.
Published: January 2005

Various mechanisms for the excitation and quenching of fluorescence are discussed. It is pointed out that the classical Stern-Volmer mechanism may apparently be obeyed in cases where the process is not that of simple absorption followed by fluorescence and collisional deactivation. For polyatomic molecules a spectroscopic examination will not always disclose definitely the nature of the emitting radical or molecule. A study of the effects of several variables on the intensity of the fluorescence will frequently give much information about the lifetimes of the emitting molecules and the course of the photochemical reactions taking place. Quantitative studies of the fluorescence in the gas phase have been made for very few polyatomic molecules. Nitrogen dioxide and acetone are cited as examples.
Vibration Spectra and Molecular Structure VIII. Absorption Spectra of Light and Heavy Phenol and Aniline Vapors
Authors: Williams V. , Hofstadter R. , Herman R. C.
Published: January 2005

The near infra-red spectra of light and heavy phenol and aniline vapors have been obtained with a rocksalt spectrometer. Comparisons have been made between the spectra of the light compounds as found in various phases, and an interpretation of certain changes occurring in the spectrum of phenol is suggested. The spectra of the heavy compounds have suggested certain assignments, such as the δ (OD) vibration at 913 cm—1 in heavy phenol and the δ (OH) vibration at 1177 cm—1 in light phenol.
Thermodynamic Properties of Hydrogen Fluoride and Fluorine from Spectroscopic Data
Authors: Murphy George M. , Vance John E.
Published: January 2005

Spectroscopic data have been used to calculate the free energy, entropy and heat capacity of diatomic HF between 298.1° and 2000°K. The required spectrum of F2 is not known but from electron diffraction data and Badger's rule, enough information has been obtained to make similar calculations to the harmonic oscillator—rigid rotator approximation. The errors in the thermodynamic quantities due to the uncertainties in the vibrational frequency and moment of inertia have been estimated. Combination of these results with thermal data has resulted in values of the free energy change of the reactions: 1/2H2+1/2F2⇌HF and F2⇌2F.
Melting as an Order-Disorder Transition
Authors: Wannier Gregory H.
Published: January 2005

In this paper the breakdown of a regular crystal pattern is studied for an atomic crystal of the diamond type. For practical reasons, the forces between the atoms are idealized into potential wells. It is then possible to study the motion of a limited number of particles. The lattice structure is introduced as long distance order in the manner developed by Bethe. The results show the existence of a phase transition where this long range order breaks down. Considerable thermodynamic inconsistencies are detected, however, and the reasons for these discrepancies are discussed.
Ions of Europium Distributed Between Different Configurations in Homogeneous Solutions
Authors: Freed Simon , Weissman S. I. , Fortess Fred E. , Jacobson H. F.
Published: January 2005

Changes in the environment of europium ions in solution bring about changes in the structure of the absorption spectrum. For example, an aqueous solution of europium chloride upon having potassium nitrate added to it gives rise to the structures in the spectra of europium nitrate, in addition to the spectrum of europium chloride. Structures in the spectra of europium salts in alcohol differ from those in water. In a mixed solvent of water and alcohol both spectra are present with relative intensities which vary according to the relative amounts of the components. Europium chloride in the mixed solvent has a spectrum which cannot be distinguished from the exact superposition of the spectra of europium chloride in pure water and in pure alcohol. However, the spectrum of europium nitrate in the mixed solvent has its lines shifted from the positions they occupy in the spectra of the nitrate in the pure solvents. The shifts seem to vary continuously with the proportions of water to alcohol. Nevertheless, the lines remain sharp as successive amounts of water are added, with no suggestion that the lines are a blur, between the spectra of the limiting concentrations. The implications of these results are briefly discussed in their bearing upon the behavior of electrolytes in mixed solvents.
The Viscosity and Molecular Diameter of Azomethane
Authors: Henkin H. , Taylor H. Austin
Published: January 2005

Measurements of the rate of flow of azomethane at low pressures have been interpreted according to Poiseuille's law corrected for slippage to give an average viscosity of 0.754×10—4 poise at 23°C. Assuming a Sutherland constant of 362 from the similar compound β-butylene the molecular diameter of azomethane is found to be 4.54A.
On the Interaction of Two Colloidal Particles, Using the Complete Debye-Hückel Equation
Authors: Levine S.
Published: January 2005

Making use of the original Debye-Hückel equation in the theory of electrolytes, an approximate method of calculating the mutual electrical energy of two colloidal particles has been developed. Only binary electrolytes (symmetrical type) have been considered. The final expression for the energy is of the form (Q02/Da){f1(R/a,κa)+(Q0/Da)2(zε/kT)2g(R/a,κa)}or ζ2Da(1+κa)2{f1(R/a,κa)+ζ2(zε/kT)2G(R/a,κa)},where Q0, a and ζ are the charge, radius and electrokinetic potential, respectively, of each particle, R is the mutual separation of the two particles, κ the characteristic quantity in the Debye-Hückel theory, being proportional to the square root of the electrolyte concentration, z—z the valency type of the binary electrolyte, D the dielectric constant of the solution, T the temperature, ε the electronic charge and k Boltzmann's constant. Contrary to the opinion held by many, it is shown that for symmetrical electrolytes, the commonly quoted restriction zεζ/kT≪1 need not be satisfied in order that the approximate Debye-Hückel equation be applicable. Provided the particle radius is not too large, the latter equation leads to fairly satisfactory values for both ζ and the mutual energy at ordinary ζ potentials. The coagulating powers of the 1–1, 2–2 and 3–3 valency types of electrolytes are studied in detail and qualitative agreement with experiment is obtained. It is shown that the stability of a sol is sensitive to changes in the ζ potential and that in comparing the relative precipitation values of the different electrolytes one must be careful of any small change in ζ. The distinction between the monovalent ions which coagulate at high concentrations and high potentials and the other ions which precipitate at lower potentials and smaller concentrations is emphasized. The energy of the two particles at large separations is again negative and there is a minimum in the energy as a function of the particle distance.
The Reaction of Atomic Hydrogen and Azomethane
Authors: Henkin H. , Taylor H. Austin
Published: January 2005

At 27°C the only reaction between atomic hydrogen and azomethane is an addition to the nitrogen double bond to produce s-dimethylhydrazine by a mechanism with a maximum activation energy of 3–4 kcal. At 110°C there is in addition to this a rupture of the C–N bond in azomethane and the N–N bond in the hydrazine producing methane and methylamine, respectively. The energy of activation of each rupture appears to be about 8 kcal. At 195°C an additional reaction is evident involving association of methyl radicals with azomethane.
Statistical Mechanics of Condensation Phenomena in Mobile Monolayers
Authors: Band William
Published: January 2005

The dissociation method developed previously is modified to cover the condensation phenomena observed in mobile monolayers. The saturated tension equations are found to depend only on the number of bonds with nearest neighbors, and the mean energy per bond per molecule in the condensed phase. Assuming six bonds with mean energy per bond 3.7×10—14 erg per molecule, good agreement is obtained with the curves published by Adam and Jessop for the fatty acids.
The Beta′-Beta Transformation in Lithium-Lead Alloys
Authors: Wilson Thomas C.
Published: January 2005

Measurements made by Grube and Klaiber in 1934 on the alloys of lithium and lead indicate that a transformation of peculiar character occurs in the beta-phase of these alloys. The behavior of this transformation under high hydrostatic pressure has been investigated by measurements of the electrical resistance. The results, together with those from rough thermal expansion measurements, indicate that the transition takes place gradually on heating from a phase of abnormally high energy and entropy content to a phase of more normal character. X-ray analyses suggest that the transition is accompanied by movements of the lithium atoms in the lattice to more orderly positions.
The Study of the Diffraction of Protons of Medium Energy by Vapor Molecules
Authors: Yearian H. J.
Published: January 2005

The diffraction of 15–20 kv protons by carbon tetrachloride vapor has been investigated with a low voltage arc source and electrostatic focusing with photographic registration. The principal difficulties encountered were with space charge dispersion of the beam near the ion source, and with neutralization of the beam as it passed through the vapor. The cross sections for neutralization and re-ionization of protons and hydrogen molecular ions in several gases and vapors were determined. The sensitivity of photographic film was found to diminish as the emulsion was outgassed but to increase fifteen-fold when it was treated with oil. When suitable precautions were taken to minimize the background scattering, diffraction patterns were obtained showing three maxima, the measurements of which are in satisfactory agreement with electron diffraction data.
Note on the Continuous Absorptions of N2O
Authors: Sponer H. , Bonner L. G.
Published: January 2005

The absorption of N2O in the long wave-length region of the near ultraviolet has been reinvestigated with an absorption tube 105 feet in length. The well-known absorption in this region has been extended and its resolution into several components is discussed. A few remarks are added about other continuous absorption regions in connection with different dissociation reactions of N2O.