bluuebunny/crossref_metadata_2025 huggingface dataset:
The Kinetics of Heterogeneous Atom and Radical Reactions. I. The Recombination of Hydrogen Atoms on Surfaces
Authors: Shuler K. E. , Laidler K. J.
Published: January 2005

The data on the kinetics of the recombination of hydrogen atoms on various types of surfaces are analyzed in the light of the theory of absolute reaction rates. Expressions are derived for the recombination coefficient and the first-order rate constant, enabling these quantities to be calculated on the basis of postulated mechanisms. It is shown that the experimental activation energies are consistent with estimates using either Hirschfelder's rule or an expression utilizing the experimental ``desorption temperature.'' For the reaction on dry oxides and dry glass good agreement is found assuming that reaction occurs between a gas-phase hydrogen atom and an adsorbed hydrogen atom, the adsorption being of the van der Waals type at low temperatures and chemisorption at higher ones. The mechanism of surface poisoning by water vapor is shown to be not due to the necessity for desorbing the water molecule: in the high temperature region it is due to an increase in activation energy, the mechanism being S–OH+H→S–O+H2; in the low temperature region to a decrease in the number of active centers, the reaction being between a gaseous atom and a van der Waals adsorbed hydrogen atom above the water layer.
On the Theory of the π-Electron System in Porphines
Authors: Simpson William T.
Published: January 2005

The failure of certain LCAO molecular orbital calculations of the spectrum of porphine is attributed to the incorrect assumption of complete ``aromaticity.'' A division of the π-electron system into non-interacting parts is supported by the fact that the dynamical properties of the divided system, as calculated by the free-electron model, are in approximate agreement with experiment. A proof of the equivalency of the LCAO method (with overlap neglected) and an approximation to the free-electron method is indicated for certain dynamical systems.
Electrochemical Thermodynamics and Kinetics of Hydrogen Overvoltage
Authors: Van Rysselberghe Pierre
Published: January 2005

The problem of hydrogen overvoltage is attacked by a method making systematic use of chemical and electrochemical potentials. More precise formulas are thereby obtained than in previous theories and a more definite interpretation of the transfer coefficient of Erdey-Grúz and Volmer is arrived at. The Tafel empirical equation is discussed and the existence, in some cases, of several Tafel regions is considered. Activation free energies, energies, and entropies for the discharge process are calculated and the mechanism involving formation of atomic hydrogen is shown to be entirely plausible.
The Physical Properties of Polonium. III. The Half-Life of Polonium
Authors: Beamer William H. , Easton William E.
Published: January 2005

The half-life of polonium has been measured by a calorimetric method. The reproducibility and precision of the data is much greater than has been previously reported. The value is found to be 138.3±0.1 percent days.
The Hydrolysis of Ferric Ion
Authors: Olson A. R. , Simonson T. R.
Published: January 2005

The first hydrolysis of ferric ion in the presence of various perchlorate salts has been studied spectrophotometrically. At a given concentration of perchloric acid, the equilibrium has been shown to depend on the concentration of perchlorate ion.
The Superficial Density of Matter at a Liquid-Vapor Boundary
Authors: Tolman Richard C.
Published: January 2005

The distribution of matter within the transition layer between the two phases of a fluid system is considered. Approximate values are obtained for the superficial density of matter Γ, calculated with reference to the Gibbs surface of tension as the dividing surface between the phases.
The Infra-Red and Raman Spectra of Dimethyl Mercury and Dimethyl Zinc
Authors: Gutowsky H. S.
Published: January 2005

The infra-red spectra of dimethyl mercury and dimethyl zinc and the Raman spectrum of dimethyl mercury have been observed. A frequency assignment has been proposed for dimethyl mercury, and that of dimethyl zinc has been modified. The results support a linear C—M—C structure, in agreement with quantum-mechanical predictions, and also D3h′ symmetry with essentially free rotation of the methyl groups. A normal coordinate analysis has been made of the fundamental frequencies and valence-type force constants deduced therefrom. The values of the force constants pertaining only to the methyl groups agree very well with values obtained in other molecules; others indicate the relatively easy deformability of the C—M—C figure axis. Differences between the dimethyl mercury and dimethyl zinc force constants indicate greater ionic character in the C–Zn bond. Values of 2.45 and 2.39×105 dynes/cm are obtained for the C–Hg and C–Zn stretching force constants. The relation of these values to current suggestions concerning the dependence of bond strengths on atomic parameters is briefly discussed.
The Infra-Red Absorption Spectrum of Mono-Deutero-Ethane under High Resolution
Authors: Posey L. R. , Barker E. F.
Published: January 2005

The infra-red spectrum of C2H5D has been investigated under high resolution. As expected, the bands corresponding to degenerate vibrations of C2H6 are split into two components with oscillations in the symmetry plane and normal to the symmetry plane respectively. Analogues of several of the inactive C2H6 frequencies have also been observed, including a pair at 1122 cm−1 and 1159 cm−1 corresponding to a Raman line of ordinary ethane which has been predicted at about 1170 cm−1 but has not as yet been found.
The Absorption Spectrum of Ethylene Oxide in the Vacuum Ultraviolet
Authors: Liu Ta-Kong , Duncan A. B. F.
Published: January 2005

The spectrum of ethylene oxide was investigated from the visible down to about 600A, with high resolution in the vacuum region. No discontinuous absorption was found above 1713A. Two Rydberg series, beginning at 1435 and 1382A were found, which converge to the same ionization potential at about 10.81 ev. Two non-Rydberg transitions were found, with origins apparently at 1713.4 and 1572.4A. An analysis and discussion is made of the spectrum. It is concluded that the Rydberg transitions arise by excitation from a molecular bonding orbital, very similar to one responsible for Rydberg series in ethylene and related compounds.
The Normal Vibrations of Polyatomic Molecules as Treated by Urey-Bradley Field
Authors: Simanouti Takehiko
Published: January 2005

A method of setting up the vibrational secular equation for polyatomic molecules of ``Urey-Bradley field'' type is described. By this method the vibration frequencies of CCl4, CBr4, CH4, CD4, CCl3Br, CCl2Br2, CClBr3, CCl3H, CCl2H2, CClH3, CCl3D, CCl2D2, CClD3, CH3D, CH2D2, and CHD3 molecules have been calculated. The 102 fundamental frequencies calculated using 28 distinct force constants are in satisfactory agreement with the observed, with a mean deviation of 1.4 percent.
The Dipole Moments of Fulvene and Azulene
Authors: Wheland G. W. , Mann D. E.
Published: January 2005

The dipole moments of fulvene and azulene have been calculated theoretically by the LCAO MO method, and have been obtained from experimental data. The experimental results support the theoretical predictions.
The Thermodynamics of High Polymer Solutions. IV. Phase Equilibria in the Ternary System: Polymer—Liquid 1—Liquid 2
Authors: Scott Robert L.
Published: January 2005

Two approximate methods of calculating equilibrium phase diagrams in ternary systems of polymer and mixed liquids have been compared with exact phase diagrams based upon the Flory-Huggins equations. Both a ``single liquid approximation'' and a ``complete immiscibility approximation'' are worthless except for the crudest qualitative considerations. Analytical expressions for the plait points of such ternary systems (a maximum of ten) have been derived. A consideration of the solubility of polymers in mixed solvents leads to the conclusion that a polymer may be completely soluble in certain mixtures of non-solvents if its internal pressure (cohesive energy density) lies between those of the two liquids and if the two liquids are themselves completely miscible. The position of the phase boundary is nearly independent of the molecular weight of the polymer for molecular weights above 10,000. Osmotic pressures in mixed solvents are discussed, and Gee's suggestion that the osmotic pressure is zero at the critical solubility limit is confirmed.
The Configuration of Real Polymer Chains
Authors: Flory Paul J.
Published: January 2005

The average configuration of polymer molecules in solution is markedly influenced by the obvious requirement, ordinarily disregarded in problems relating to molecular configuration, that two elements of the molecule are forbidden from occupying the same location in space. The influence of spatial ``interferences'' between different segments of the molecule on its average configuration has been investigated by statistical and thermodynamic methods.

It is shown that if the average linear dimension of a polymer chain is to be taken proportional to a power of the chain length, that power must be greater than the value 0.50 previously deduced in the conventional ``random flight'' treatment of molecular configuration. This power should approach 0.60 for long chain molecules in good solvents. With increase in size of the solvent molecule, the influence of interference on molecular configuration diminishes, vanishing entirely in the extreme case of a solvent which is also a high polymer. The effect of a heat of interaction between solvent and polymer may also be incorporated quantitatively in the theory. A positive heat of mixing (poor solvent) tends to offset the expansive influence of interference, and the exponent referred to above tends to approach 0.50. The results are of foremost significance in the interpretation of the intrinsic viscosity and its dependence on the polymer constitution and on the solvent. It is pointed out that the spatial dimensions of the irregularly coiled polymer molecule cannot be correlated directly with hindrance to rotation about chain bonds, unless the expansion of the configuration due to interference and the effects of the heat of dilution are first of all taken into account.
An Electrostatic Theory of the Potential Barriers Hindering Rotation around Single Bonds
Authors: Lassettre Edwin N. , Dean Laurence B.
Published: January 2005

A number of simplifying hypotheses concerning the distribution of molecular electrons are discussed. On the basis of these hypotheses, the contribution of electrostatic forces to the interaction energy between two non-adjacent covalent bonds in a molecule has been estimated by expansion of the electrostatic potential in inverse powers of the distance. The expansion is carried as far as the quadrupole term. A discussion is given of the magnitudes to be expected for quadrupole moments of covalent bonding distributions. It is found that the electrostatic interactions, when extended to the quadrupole approximation, are sufficient to account for potential barriers hindering internal rotation in ethane, methylamine, methyl alcohol and dimethylacetylene. Using reasonable assumptions concerning the distribution of unshared electron pairs, the unsymmetrical configuration of hydrogen peroxide is found to be stable, in agreement with experiment. Extension of the treatment to the more complex molecules propane, isobutane, and neopentane indicates that the interaction between non-adjacent groups is not negligible. A relation between bond quadrupole moments and interatomic distance is given, and possible refinements to the treatment are discussed.
The Mercury Photosensitized Polymerization of Cyclopropane
Authors: Gunning H. E. , Steacie E. W. R.
Published: January 2005

An investigation has been made of the polymerization of cyclopropane with mercury (3P1) atoms in a static system over the pressure range from 1–400 mm at 30°C. The only important product of the reaction is a liquid polymer with the formula (C3H6)n, where n is probably about 6. Small amounts of other products, of low molecular weight, are present at initial pressures below 10 mm. Data are presented which show that propylene is formed only at low initial pressures, suggesting its origin from the collision of trimethylene biradicals with the wall.

The over-all rate of consumption of cyclopropane becomes independent of initial pressures above 40 mm. The quantum yield of cyclopropane disappearance in the complete quenching region is 0.136.

A mechanism is proposed for the polymerization involving the initial formation of an energy-rich trimethylene biradical by the reactionC+Hg(3P1)→R1*+Hg(1S0).The activated radical can then either reform cyclopropane upon collision or form a higher biradical: R1*+C→2C,R1*+C→R2*,etc.,where C = cyclopropane, R1 = ·(CH2)3·, and R2 = ·(CH2)6·. Chain termination will occur when the polymer biradical can no longer furnish sufficient energy to break the C–C bond in cyclopropane. The radical will then stabilize itself by a proton shift. On the basis of the above mechanism, combined with the analytical data, reaction (2) must be at least 43 times faster than reaction (3).

Evidence is also presented for the fact that cyclopropane does not react with the H atoms formed by the collision of Hg(3P1) atoms with hydrogen.
The General Solution of the Secular Equation of Second Degree, with Application to the Class A1 Vibrations of the Symmetrical Triatomic Molecule
Authors: Torkington P.
Published: January 2005

Various solutions of the secular equation of second degree, giving the force constants, normal coordinates, and potential energy distributions in terms of the fundamental vibration frequencies and molecular constants, have been found and their significance discussed. General formulas are obtained for certain critical solutions and illustrative numerical results given for a series of eight symmetrical triatomic molecules, with curves covering all possible solutions in three typical cases. The solution in which the ratios of the contributions to the potential energy from the two square terms in the valence-force potential energy expression are mutually reciprocal in the two normal modes is shown to be universally applicable; that in which the normal coordinate for the vibration of higher frequency is identical with the corresponding valence-force symmetry coordinate is also quite satisfactory. Both always give real results. Alternative solutions are suggested for use when the difference in frequency of the two modes is small.
Hydrogen Peroxide in the Thermal Hydrogen Oxygen Reaction I. Thermal Decomposition of Hydrogen Peroxide
Authors: McLane C. K.
Published: January 2005

The decomposition of hydrogen peroxide (at partial pressures of one to two millimeters of mercury) was studied in the presence of one atmosphere of oxygen or nitrogen by the use of a flow system. The concentration of H2O2 was measured photometrically, using the continuous ultraviolet absorption of this compound. Determination by this means was more rapid, and offered less chance for errors of manipulation than conventional chemical analysis. A first order reaction with an activation energy of 40 kcal./mole was found in the neighborhood of 520°C. Evidence is presented to support the conclusion that the reaction is partly, at least, homogeneous in boric acid treated vessels at temperatures in the 470 to 540°C range.
Some Magnetic Properties of Manganese-Activated Luminescent Solids
Authors: Johnson Peter D. , Williams Ferd E.
Published: January 2005

The specific susceptibilities of a series of manganese-activated zinc fluoride phosphors and their components have been measured. The unexcited manganese was found to be in the divalent 6S state. There is evidence for exchange demagnetization of adjacent paramagnetic activator ions.

The change in paramagnetic susceptibility with excitation, predicted by Williams and Eyring [F. E. Williams and H. Eyring, J. Chem. Phys. 15, 289 (1947)] to explain the long non-temperature-dependent lifetimes of the emitting states of luminescent solids containing paramagnetic activators, has been measured for manganese-activated zinc fluoride. Radiation from a high voltage discharge lamp was used to excite the phosphor in a vacuum magnetic balance having a sensitivity of 10−6 dyne per mm scale deflection. The observed change in susceptibility corresponds to a decrease of the order of magnitude of one Bohr magneton per excited activator ion.
Quasi-Chemical Theory of Order for the Copper Gold Alloy System
Authors: Li Yin-Yuan
Published: January 2005

Yang's general quasi-chemical theory of superstructure is further generalized in terms of the atomic distribution on sublattices of any number and of any geometrical arrangement. The possibility of the formation of different types of long-distance order due to the different recombinations of sublattices is discussed. By making use of this theory the behavior of the general Cu–Au system at very low temperatures and its phase diagram are shown. The critical temperature, latent heat, curve of long-distance order and energy vs. temperature for the CuAu tetragonal crystal are obtained. Our results are found to be quite different from those of Shockley's theory. All the experimental findings that are available to the author have been used for comparison with our results; so far no qualitative disagreement can be shown.
Transport Properties of Multicomponent Gas Mixtures
Authors: Curtiss Charles F. , Hirschfelder Joseph O.
Published: January 2005

Equations are derived for the viscosity, ordinary (pressure) diffusion, and thermal diffusion of multicomponent mixtures of gases. The ordinary diffusion velocities are expressed in terms of the usual diffusion coefficients for binary mixtures. The analysis is an extension of the work of Chapman and Cowling. It is shown that the Chapman-Cowling and Enskog procedure can be justified on the basis of a variational principle. This variational principle should be generally applicable to a large class of problems.
The Effect of Non-Homogeneity of Molecular Weight on the Scattering of Light by High Polymer Solutions
Authors: Brinkman H. C. , Hermans J. J.
Published: January 2005

The general theory of the turbidity of a mixture of many components is applied to a solution of homologous polymers.

It is found that the concentration dependence of the turbidity is intimately related to that of the osmotic pressure. The molecular weight distribution does not have any influence on the concentration dependence of the turbidity.
The Vapor Pressure, Orthobaric Liquid Density, and Critical Constants of Isobutane
Authors: Beattie James A. , Edwards David G. , Marple Stanley
Published: January 2005

The vapor pressures and orthobaric liquid densities of isobutane (propane−2-methyl) were measured from 30° to 125°C. The equation log10p (normal atmos.)=4.31269–1126.71/T  (T=t∘C (Int.)+273.13)gives a fair representation of the vapor pressures.

The critical constants of isobutane are determined by the compressibility method. They are: tc=134.98±0.05°C (Int.), pc=36.00±0.05 normal atmos., vc=0.263 liters per mole (4.53 ml per g), dc=3.80 moles per liter (0.221 g per ml). The uncertainty in the critical volume and density is 2 percent.
Directed Valence as a Property of Determinant Wave Functions
Authors: Zimmerman Howard K. , Van Rysselberghe Pierre
Published: January 2005

Making use of Slater's extension of the Heitler-London method, it is shown that the directional properties of carbon valences are a logical consequence of the combination of the hydrogen-like individual electron orbitals of carbon into a determinant wave function. It is possible to separate the radial and angular parts of such a function by factoring. Partial differentiation of the factored function with respect to the angular variables leads to proof of the directional properties, while partial differentiation with respect to the radial variable shows that, as long as all valence electrons are at equal distances from the nucleus, the electron density is maximum at points located on a sphere whose radius is calculated.
The Formula of Uranyl Ion
Authors: Crandall Howard W.
Published: January 2005

The exchange of oxygen between uranyl ion and water was studied using oxygen 18 as a tracer. The results showed that the formula of uranyl ion in dilute hydrochloric acid solution is UO2++, neglecting any anion complexing, as distinguished from U(OH)4++, unless in U(OH)4++ two of the oxygen atoms are much more weakly bonded than the other two. The UO2++ ion is covalently bonded in dilute hydrochloric acid solution as well as in crystalline uranyl chloride. The Raman spectrum of uranyl perchlorate was measured and the available Raman spectra of uranyl salts are interpreted considering the effects of complex ion formation.
Determination of the Density of UF6 from the Sinking Temperatures of Glass Floats
Authors: Hoge Harold J. , Wechsler Martin T.
Published: January 2005

By observing the temperatures at which glass bodies were just equal in density to the liquid, the density of liquid UF6 was measured along the saturation curve from the triple point (64.052°C) to 162.59°C. The density of the liquid at the triple point was found to be 3.630 g cm−3. Results of an earlier investigation are also reported. They confirm the later data, and lead to a value of 4.87 g cm−3 for the density of the solid at 62.5°C.
The Quantum Mechanics of Chemical Kinetics of Homogeneous Gas Phase Reactions I. General Considerations
Authors: Golden Sidney
Published: January 2005

From the zeroth order Born-Oppenheimer approximation to the wave functions of a molecular system and the first order time-dependent perturbation theory of quantum mechanics it has been possible to deduce: (1) the adiabatic hypothesis; (2) the dependence of the rate of homogeneous gas phase chemical reactions upon the composition of reaction mixtures; (3) the condition for zero net rate of reaction, which corresponds precisely to the statistical mechanical condition for equilibrium; (4) the dependence of the chemical reaction rate upon the temperature.

Heuristic considerations transcribe the quantum mechanical result into terms of the collision theory and the activated complex theory of chemical reactions.
The Hot Atom Chemistry of the Propyl Bromides
Authors: Friedman Lewis , Libby W. F.
Published: January 2005

The chemical effects of the recoil from the capture gamma-radiation produced by the (n, γ) reaction on bromine 81 in both normal and isopropyl bromides have been investigated. It is found that the principal part of the radiobromine resisting aqueous extraction, that is, organically combined, is propyl bromide. The ratio of normal to isopropyl bromide formed by irradiation of either normal or isopropyl bromide is found to be about 2.5. The irradiation of propyl bromide cooled to liquid nitrogen temperatures produced no change in the yield of normal and isopropyl radiobromides as compared with the results for the liquids at room temperature. In direct contrast, however, the yield of the dibromides requiring hydrogen substitution was much larger in the case of the low temperature solid, the percentage yield of dibrom rising about fourfold. These results are interpreted as evidence that the bromine substitution is a reaction occurring largely in the high energy range where the chemical bonds involved are negligible, and that the hydrogen substitution occurs in the lower energy range where the recoiling bromine atoms collide with the molecule as a whole in an inelastic manner rather than with a single atom, as is postulated in the high energy range. The difference in temperature dependence of the two types of substitution reaction would appear to arise from the difference in magnitude of the energies involved. The fact that the irradiation of isopropyl bromide produces 2.4 times as much normal bromide as iso bromide and the same relative amounts are observed in the irradiation of normal propyl bromide is taken as further evidence of the extremely energetic nature of the bromine substitution reaction, the free radical apparently having sufficient energy to isomerize before recombination occurs in the solvent ``cage.''
A General Method of Obtaining Molecular Symmetry Coordinates
Authors: Nielsen J. Rud , Berryman L. H.
Published: January 2005

A general method of obtaining molecular symmetry coordinates based on the algebra of group representation theory is described. The method is direct and involves no trial and error. It presupposes a knowledge of the irreducible representations of the molecular symmetry group rather than merely of their characters. The orthogonality properties of the symmetry coordinates are derived. As an example, the method is applied to boron trifluoride (D3h), with the use of both internal and Cartesian coordinates.
The Relative Reaction Velocities of Isotopic Molecules
Authors: Bigeleisen Jacob
Published: January 2005

The rate constants for competitive reactions of isotopic molecules are considered from the theory of ``absolute rates'' and the collision theory. Formulas are derived for the ratio of the rate constants and the difference in the activation energies for reactions of isotopic molecules. The difficulties in the a priori calculation of relative rates are pointed out and discussed.

In general the rate constant for the light molecule will be greater than that of the heavy molecule. It is shown that the maximum ratio in the rates occurs when the isotopic atom is essentially free in the activated complex. The conditions for the rate constant of the heavy molecule to exceed that of the light one are formulated.

It is shown that the difference in activation energies covers the range from zero to the difference in the differences in the zero-point energies of the reacting molecules and their respective activated complexes.
Thermodynamics of Crystallization in High Polymers. VI. Incipient Crystallization in Stretched Vulcanized Rubber
Authors: Fox Thomas G. , Flory Paul J. , Marshall Robert E.
Published: January 2005

Experimental determination of the elongation at which crystallization commences in vulcanized rubber has been attempted through measurement of density changes by a hydrostatic method. The critical elongation for incipient crystallization appears to depend on the temperature in approximate accordance with theoretical prediction. Crystallization sets in at an elongation well below that at which the stress-strain curve assumes a steep slope.
Punched Card Calculation of Resonance Energies
Authors: Oakley Margaret B. , Kimball George E.
Published: January 2005

The calculation of resonance energies can be greatly simplified by using punched card machines. Two methods are developed. The first is easy to apply and works well for 8-, 10-, and 12-electron problems. This is used for naphthalene. The results lend themselves well to a bond probability calculation from which bond distances in good agreement with other methods are obtained. The second procedure is longer, but makes possible the calculation of anthracene and phenanthrene resonance energies. These are −2.951α and −3.019α, respectively. Bond probabilities and lengths were also calculated from these data.
The Normal Vibrations of Polyatomic Molecules as Calculated by Urey-Bradley Field. II. Vibrations of Polythene, Ethane, and Their Deuterium Compounds
Authors: Simanouti Takehiko
Published: January 2005

Assuming the Urey-Bradley field as the type of intramolecular potential equations to calculate five optically active frequencies of polythene molecule were derived. If we assume as force constants KCH=4.2, HHCH=0.15, FHH=0.1, FHC=0.4, FHH′=0 and FHC′=−0.05 (105 dynes/cm), the observed frequencies of (CH2)n and (CD2)n as well as those of CH4, CD4, C2H6, C2D6, etc., were explained satisfactorily.
Compressibility of Gases at High Temperatures. II. The Second Virial Coefficient of Helium in the Temperature Range 0°C to 600°C
Authors: Schneider W. G. , Duffie J. A. H.
Published: January 2005

The second virial coefficient of helium was measured in the temperature range 0° to 600°C by an expansion procedure previously described. Within our limits of error, estimated to be approximately 0.5 percent at 0° and approximately 1 percent at 600°, the results (expressed in Amagat units of volume) are given by: 103BT=0.5485–0.1315×10−3T+(3.754/T) where T is in °K. A comparison with existing data is given.
Catalysis on Non-Uniform Surfaces
Authors: Halsey G. D.
Published: January 2005

Using the ammonia decomposition as an example, the kinetics of a heterogeneous reaction are discussed. On a continuously non-uniform surface, no single reaction step is the limiting one; on the optimum sites two reaction steps are equally slow. The expression for over-all velocity is developed, and solved exactly for the case of an exponential distribution of activation energies. It appears that if the distribution is broad, its exact shape is unimportant, but that a factor r, connected with the amount of adsorption energy available for catalytic work, is important. It is shown that for a broad distribution, the pressure dependence of the over-all rate is the same as the pressure dependence on the optimum sites. Because the position of the optimum depends on pressure, one cannot assume that the surface is ``effectively uniform.'' The simplest of ammonia kinetics is discussed, but it appears that on a non-uniform surface, much more extensive experiments than have been available are necessary to elucidate properly the kinetics of a reaction.
Statistical Mechanics of Adsorption. VI. Localized Unimolecular Adsorption on a Heterogeneous Surface
Authors: Hill Terrell L.
Published: January 2005

The Langmuir isotherm for localized unimolecular adsorption is generalized (using statistical methods) in order to discuss adsorption on a heterogeneous surface, with and without interactions between adsorbed molecules. The configurational entropy, and the nature of the phase changes on a random heterogeneous surface are discussed. In particular, on this type of surface, the theory predicts, at least for one special case, that condensation will occur in two steps (instead of the customary one step) at low enough temperatures.
Statistical Mechanics of Adsorption. VIII. The Statistical Analogue of the B.E.T. Constant a1b2/b1a2 for Simulated Benzene and Hydrogen Iodide Molecules on Graphite
Authors: Drenan J. W. , Hill Terrell L.
Published: January 2005

The approximate study of the restricted rotation of molecules near a surface is extended to an unsymmetrical diatomic molecule, hydrogen iodide, and a ring molecule, benzene, for a graphite surface in each case. Calculations of the factor R in the BET constant C=R exp(ε1—Λ)/kT are carried out for these cases. R is found to be of the same order of magnitude (2–20) as for the symmetrical diatomic molecule.
Determination of Electronic Structure of Molecules from Nuclear Quadrupole Effects
Authors: Townes C. H. , Dailey B. P.
Published: January 2005

Nuclear quadrupole coupling constants in molecules depend on the nuclear quadrupole moments and the variation in electrostatic field at the nucleus. It is shown that this variation of electric field is usually simply related to the molecular electronic structure, being primarily dependent on the way in which valence electrons fill the lowest-energy p-type orbits. Structural information which can consequently be obtained from known quadrupole coupling constants is discussed. Hybridization of the normal covalent bonds of N, Cl, and As with at least 15 percent s character is clearly shown. The alkali halides appear to be almost purely ionic; the quadrupole coupling data allow no more than 3 percent covalent character. In addition to molecular structure, some nuclear quadrupole moments are approximately evaluated by use of the theory developed here.
Photomagnetism. Determination of the Paramagnetic Susceptibility of a Dye in Its Phosphorescent State
Authors: Lewis G. N. , Calvin M. , Kasha M.
Published: January 2005

The molar paramagnetic susceptibility of acid fluorescein dye in its 2-sec. phosphorescent state in boric acid glass at 25°C has been measured directly by means of a modified Theorell microbalance. The steady state concentration of phosphorescent state molecules was 1.96×10−8 mole per cm length of sample, calculated from optical intensity integrals and phosphorescence saturation curve data. The measured boom displacement was 4.04×10−3 cm, corresponding to a force of 1.07×10−2 dyne. The calculated value of the molar paramagnetic susceptibility is 3090×10−6 c.g.s. units, which agrees with the measured value for the susceptibility of the 3Σ ground state of oxygen within the estimated maximum experimental error of 13 percent.
The Magnetic Susceptibility of Potassium Ferrate
Authors: Hrostowski Henry J. , Scott Allen B.
Published: January 2005

A method of preparation of potassium ferrate of 97 percent purity is described. Although the product contained an inseparable ferromagnetic impurity, the susceptibility of the ferrate was determined by extrapolation to infinite field strength of data obtained by the Gouy method. The observed effective magnetic moment of the ferrate ion agrees approximately with that expected for hexavalent iron.
The Compressibility of, and an Equation of State for Gaseous Isobutane
Authors: Beattie James A. , Marple Stanley , Edwards David G.
Published: January 2005

The volumetric behavior of gaseous isobutane from 150° to 300°C and from 1.0 to 8.0 moles per liter has been studied. The constants of the Beattie-Bridgeman equation of state for gaseous isobutane are R=0.08206, A0=16.6037, a=0.11171, B0=0.23540, b=0.07697, c=300×104 in units of normal atmospheres, liters per mole, degrees Kelvin.
Hexacovalent Bond Orbitals II
Authors: Duffey George H.
Published: January 2005

Further calculations are reported on the set of trigonal prism orbitals introduced in paper one of this series. The strongest orbitals found have a strength equal to 2.989. The results are used in discussing the difference in stability between these orbitals and the octahedral orbitals in structures of the following types: [Complex chemical formula], Fe(CN)6≡, and SF6.
The Energy of Interaction between Two Hydrogen Atoms
Authors: Hirschfelder J. O. , Linnett J. W.
Published: January 2005

The energy of interaction between two hydrogen atoms at intermediate to large separations is determined by the use of the variational principle applied to a wave function in which both ionic and polarization terms are included. The binding energy is known accurately in the neighborhood of the equilibrium separation from Rydberg's analysis of the experimental vibrational spectrum. At very large separations the van der Waals' energy has been calculated accurately by Pauling and Beach. Our calculations extend from the smallest to the largest internuclear distances. For the normal hydrogen molecule we compute a binding energy of 4.25 ev as compared to the experimental value of 4.74 ev. By comparing our calculations at small separations with Rydberg and at large separations with Pauling and Beach we obtain a most likely potential energy curve for all separations. Similarly we obtain a most likely potential energy curve for the 3Σ excited state of hydrogen by comparing with the accurate results of James, Coolidge, and Present. Many new molecular integrals were evaluated and old ones were recalculated to obtain greater accuracy. Convenient tables of these integrals together with all of the calculational detail is given.
The Structure of Hexamethylcyclotrisiloxane as Determined by the Diffraction of Electrons on the Vapor
Authors: Aggarwal Eleanor H. (Weller) , Bauer S. H.
Published: January 2005

Hexamethylcyclotrisiloxane vapor has been shown to have a structure incorporating a planar ring with larger oxygen valence angles (125±5°) than silicon valence angles (115±5°); the methyl groups extend above and below the plane of the ring, their equilibrium bond positions making a probable angle of 112±6° with silicon, the temperature motion of the methyl groups allowing an average change in the interatomic distances involved of about 0.09A, as compared with the normal temperature motion change of about 0.03A. The Si–O distances are 1.66±0.04A and the Si–C distances are 1.88±0.04A.

The shortness of the Si–O distance suggests a larger ionic character of the bond than that indicated by the electronegativity table.
Solubility Relations in Ternary Solid Solutions of Ionic Compounds
Authors: Wagner Carl
Published: January 2005

The variation of the solubility of a solute due to the presence of a second solute in a solid ionic compound as solvent is investigated theoretically with the aid of the ideal law of mass action. Ions of the solvent in interstitial positions, cation and anion vacancies, quasi-free electrons, and electron holes are to be taken into account in the same manner as the constituents of conventional chemical systems. The theoretical conclusions are illustrated by experimental data, however, qualitatively rather than quantitatively.

The solubility of lead chloride in solid silver chloride is decreased by presence of cadmium chloride. The solubility of iodine (or cupric iodide) in cuprous iodide is likewise decreased by presence of cadmium iodide. The behavior of the corresponding bromide system is analogous. Conversely, gallium oxide increases the solubility of zinc in zinc oxide. The phenomena to be expected in lead sulfide as solvent are more complicated, since this substance can dissolve both excessive lead and excessive sulfur.

The oxidation rate of nickel is increased by presence of chromium and manganese, whereas the chlorination rate of silver is decreased by presence of lead and cadmium chloride.
The Thermodynamic Functions of Methyl Mercaptan and Dimethyl Sulfide
Authors: Binder John L.
Published: January 2005

The entropies, free energies, heat capacities and heat contents of methyl mercaptan and dimethyl sulfide have been calculated from 298.16°K to 1500°K at 100°K intervals. The free energies of formation of these compounds have also been calculated for this temperature range based both on sulfur gas and rhombic sulfur as the standard states of sulfur.
Chemical Effects Accompanying the Decay of Mn51
Authors: Burgus W. H. , Kennedy J. W.
Published: January 2005

An investigation has been made of the chemical forms assumed by Cr51 when it is produced by positron decay of Mn51 under a variety of conditions. The data have shown that the oxidation state of the parent Mn51 plays an important role in determining the oxidation state of daughter Cr51. By variation of experimental conditions some information has been obtained regarding the types of chemical reactions undergone by the Cr51. These reactions have also been shown to play important roles in determining the ultimate chemical form of daughter Cr51.

The complexity of the factors determining the chemical forms of Cr51 after Mn51 decay has been pointed out, and possible explanations of some of the observed phenomena have been suggested. We believe the results are consistent with the hypothesis that appreciable ionization in the valence shell accompanies the beta-decay process.

Incidentally it has been demonstrated that the manganese isotope of 44-min. half-life (Mn51) decays to the chromium isotope of 26-day half-life (Cr51).
The Infra-Red Spectrum of Chloroacetylene and Deuterochloroacetylene
Authors: Richardson W. S. , Goldstein J. H.
Published: January 2005

The vapor phase infra-red spectra of the molecules HCCCl and DCCCl have been investigated in the region 2μ to 30μ, and four of the five fundamentals have been identified for each molecule. Force constants have been calculated for the stretching modes of vibration assuming a linear structure. The bond stretching force constants have the values: fCH = 5.88, fCC = 14.9, fCCl = 5.51 all in units of 105 dynes/cm. The effect of resonance between the covalent structure, H–C≡C–Cl, and the structure H–C=C=Cl+ in stiffening the carbon-chlorine bond is discussed.
The Intensities of Several of the Infra-Red Absorption Bands of Cyanogen and Cyanogen Chloride
Authors: Nixon Eugene R. , Cross Paul C.
Published: January 2005

Measurement of the absolute intensities of several infra-red absorption bands of cyanogen and cyanogen chloride gives the following values in cycles per cm at N.T.P. CyanogenBandIntensity2150 cm−190×1010Cyanogen chlorideBandIntensity714 cm−117×10102214 cm−1220×1010

Values of the variation in bond moments with change in bond length are calculated on the basis of bond moment additivity. This leads to widely different values of this derivative for the CN bond in the two molecules.

The infra-red spectrum of cyanogen chloride from 2 to 20 microns is reported.
Oxygen and Nitrogen Isotope Effects in the Decomposition of Ammonium Nitrate
Authors: Friedman Lewis , Bigeleisen Jacob
Published: January 2005

The isotopic composition of the products of the controlled thermal decomposition of ammonium nitrate has been studied. It has been found that small amounts of water are necessary to initiate the decomposition of ammonium nitrate. N15H4NO3 has been found to yield exclusively the isomer N15N14O. Some inferences are drawn from this observation regarding the mechanism of the reaction.

Oxygen and nitrogen isotope effects accompanying the decomposition have been studied with material of ``natural'' isotopic composition. Satisfactory agreement is found between the experimental results and theoretical calculations.

A method for the isotopic analysis of nitrates for O18 is outlined.
LCAO Self-Consistent Field Calculation of the π-Electron Energy Levels of cis- and trans−1,3-Butadiene
Authors: Parr Robert G. , Mulliken Robert S.
Published: January 2005

The π-electrons of the molecules cis- and trans−1,3-butadiene are treated by the method of antisymmetrized products of molecular orbitals, the molecular orbitals being taken as linear combinations of 2pπ-Slater atomic orbitals with effective charge 3.18. The best ground state LCAO molecular orbitals obtainable from these are found by application of a method recently proposed by Roothaan which is based on the variational theorem, and the π-electron energy of the ground state is calculated. Including a correction for nuclear repulsions, the trans- form is computed to be 0.12 ev more stable than the cis-form. Using the ground state orbitals to build up excited state wave functions, the energies of four singly excited singlet states and the corresponding triplet states are calculated, there resulting for the average of the lowest singlet and triplet states the excitation energy 5.4 ev for cis- and 5.7 ev for trans-, the experimental value for the lowest singlet state (probably for trans-) being 6.0 ev. The first ionization potential is computed to be 9.7 ev for both cis- and trans-, whereas the observed value is 9.1 ev. No extra-geometrical empirical data are used except in the calculation of ionization potentials, where the value − 11.28 ev based on atomic spectroscopic data is used for the energy of a 2pπ-electron in a carbon atom in its valence state.
Ultrasonic Classification of Organic Liquids
Authors: Verma Gurdeva Sharan
Published: January 2005

Ultrasonic absorption in various organic liquids at four different frequencies 1.00, 1.46, 2.89, and 4.00 Mc as well as their temperature coefficient of absorption (25°C to 60°C) have been studied by ultrasonic interferometer. Liquids have been classified into four broad groups, Class I in which absorption due to changes in the heat content of the medium predominates, Class II in which absorption caused by structural changes in the quasi-crystalline structure of the liquid state predominats, Class III in which viscosity of the medium alone accounts for absorption and Class IV where absorption is not proportional to the square of the frequency.
Correlation of Ionic and Atomic Radii with the Heat of Hydration
Authors: Robertson W. D.
Published: January 2005

It is shown that Pauling's ionic and atomic radii may be correlated with the ionic heat of hydration in a manner which provides a method of intercomparison of the different radii and demonstrates their self-consistency. The correlation also indicates significant differences between ionic and atomic radii which may be interpreted in terms of the ion-dipole interaction theory of solutions.
Transport Properties of Dense Media. I. Thermal Diffusion in Isotopic Mixtures of Gases
Authors: Robb W. L. , Drickamer H. G.
Published: January 2005

Based on Meixner's thermodynamics for irreversible processes, and the work of Haase, an equation for the thermal diffusion ratio α, which can be evaluated from the equation of state, is presented.

Using van der Waals' equation, α's are calculated in the critical region and compared with data for ethane-xenon. The equation reproduces all the essential features of the experimental results.

Calculations made for a mixture of isotopes indicate that the effect of pressure on α cannot be attributed to selective clustering.
Fluorescence Studies of Some Simple Benzene Derivatives in the Near Ultraviolet: II. Toluene and Benzonitrile
Authors: Bass Arnold M.
Published: January 2005

The fluorescence spectra of toluene and benzonitrile have been studied using various sources of excitation. In both cases, discrete spectra have been observed in the near ultraviolet. The spectrum of toluene shows about 100 bands while that of benzonitrile shows about 140 bands. In both cases, there is good agreement with the absorption spectra. Progressions are noted and assignments are made for some of the vibrations in accordance with the symmetry properties of the molecules.
Intermolecular Forces in Benzene and Ammonia
Authors: Myers Vernon
Published: January 2005

The intermolecular forces between benzene molecules and between ammonia molecules are computed in a semi-empirical manner. The long-range attractive forces are calculated from optical dispersion data and dipole moments, and the short-range repulsive forces are estimated from second virial coefficients.
Determination of Molecular Shape by Osmotic Measurement
Authors: Isihara A.
Published: January 2005

The second coefficient A2 of osmotic pressure π of high-polymer solutions is calculated in the case of the rigid ovaloid. A2 is a function of the molecular shape and thus we can determine the shape of high polymers.
The Magnetic Anisotropy of α—NiSO4·6H2O between 13 and 295°K. A Torsion Balance for Magnetic Anisotropy Measurements
Authors: Stout J. W. , Griffel Maurice
Published: January 2005

The magnetic anisotropy of single crystals of α—NiSO4·6H2O has been measured at temperatures between 13 and 295°K. Two crystals of different origin gave concordant results. The difference in magnetic susceptibility between directions parallel and perpendicular to the tetragonal crystallographic axis is given by χ⊥−χ‖=1.37×10−5+1.502×10−2/T+1.686/T2. The susceptibility difference was independent of field strength up to 10,000 gauss over the temperature range investigated. The results are discussed in connection with the theoretical treatment of the susceptibility of nickel salts by Schlapp and Penney. A torsion balance for the magnetic anisotropy measurements is described.
Raman Spectra of Hydrocarbons. V. n-Hexane, n-Heptane, 2-Methylpentane, 3-Methylpentane, 2,4-Dimethylpentane, and 2,3-Dimethylbutane
Authors: Cleveland Forrest F. , Porcelli Pasquale
Published: January 2005

Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors are given for the above named hydrocarbons in the liquid state. The relative intensities and depolarization factors were obtained by use of a Gaertner microdensitometer. The depolarization factors were determined by a well-tested, single-exposure method. The previous data have been collected, tabulated, and compared with the present results, and probable values and average deviations are listed.