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  • Springer  (12)
  • 1955-1959  (12)
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  • Springer  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Metallurgist 2 (1958), S. 168-169 
    ISSN: 1573-8892
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 6 (1957), S. 1334-1347 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1. The adsorption energy of nonpolar molecules is calculated by a method which takes into consideration three terms in the potential of the dispersive forces by means of constants calculated on the basis of the polarizabilities and magnetic susceptibilities, Other factors taken into consideration in the development of the method are inductive potential (through the mean polarizability of the adsorbate and the mean electrostatic field of the adsorbent) and the repulsion potential (through an exponential constant calculated from the individual constants of adsorbent and adsorbate and with summation of all of the interactions of the given energy center of the molecule of adsorbate over all of the centers of the lattice of the adsorbent). The exponential repulsion constant was determined from the minimum condition of the summed energy of all of the interactions at the equilibrium distance from the adsorbent surface. 2. The calculated values of the energy of adsorption of noble gases, nitrogen and thirteen hydrocarbons of various structures (normal and isomeric alkanes, an alkene, cyclanes and aromatics) on graphite are close to the measured heats of adsorption on graphitized carbon blacks. 3. The calculated values of the energy of adsorption of n-alkanes, benzene and toluene on magnesia are likewise close to the measured heats of adsorption. 4. In the case of adsorption on graphite the contributions of the first, second and third terms of the energy of the dispersive forces and the absolute value of the repulsion energy constitute 90–95, 5–10, 0.5–1 and 35–40%, respectively, of the total energy of the dispersive forces for the investigated adsorbates. In the case of adsorption of MgO the contributions of the first, second, and third terms of the energy of the dispersive forces, the energy of the inductive forces and the absolute magnitude of the repulsion energy constitute about 81–83, 12–14, 3, 2 and 42–48%, respectively, of the total energy of the attractive forces (dispersive and inductive).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 8 (1959), S. 213-217 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1) We used the adsorption method to investigate the changes in the pore structure of large-pore magnesium hydroxide during thermal treatment in vacuo. 2) During the transition from magnesium hydroxide to oxide at 350° the specific surface increases due to the formation of fine cracks in the primary flakes constituting the large-pore shell of magnesium hydroxide. When the sample is heated at 500° the specific surface somewhat decreases due to a fusion of these fine cracks. The structure of large capillaries does not change at 350 and 500°. 3) When heated at 1000° (in vacuo) magnesium oxide undergoes noticeable sintering, but the dimensions of large pores still do not decrease appreciably. At 1400° the large pores also undergo extensive constriction.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 6 (1957), S. 1052-1061 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1. Determination of the absolute isotherms of adsorption and of the differential heat of adsorption of vapors of n-pentane, n-heptane and n-octane on graphitized carbon black were carried out in a calorimeter with constant heat exchange. These isotherms were compared with those previously determined for n-hexane. 2. The thermodynamic characteristics of the adsorption of the vapors and of wetting were determined for these hydrocarbons. Standard values of the heat, the total and free energy and the entropy of adsorption are linear functions of the number of carbon atomsn in the molecule of these hydrocarbons. The heat of. wetting is independent ofn. 3. An approximate equation is given for calculation of the constant of the adsorption isotherm of the above n-alkanes on graphite for differentn and for various temperatures. The equation is consistent with the experimental isotherms. 4. The theoretically calculated dependence of the energy of adsorption of n-alkanes on graphite — Φ = = 0.9 + 1.85 n kcal/mole adequately represents the heats of adsorption of these hydrocarbons on the homogeneous surface of graphitized carbon black.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 8 (1959), S. 1155-1165 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The details of an earlier theoretical calculation of the energy of adsorption of simple and complex non-polar molecules on graphite were presented. The power sums of type $$\Sigma r_{i\bar j} ^n $$ were calculated for different distances of the adsorbate molecule from the external base plane of graphite, at n=6, 8, 10 and 12, as were also the exponential sums of type $$\Sigma e - ^{r_{ij} /} \rho $$ , at δ=0.28 A. Using approximate quantum mechanics equations, we calculated the constants of three terms of the energy of dispersive attraction, and also the constants of repulsion from the equilibrium condition. The additive scheme was used to calculate the potential curves and equilibrium adsorption energies of complex molecules.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 7 (1958), S. 504-505 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1. In its radiolysis ethylene is converted mainly into butane, acetylene, and liquid hydrocarbons. 2. Apart from butane and acetylene, the gaseous products include small amounts of CH4, C2H6, C4H8, and H2 and also traces of propene. The liquid products boiling up to 130° consist of C6 and C8 aliphatic hydrocarbons. The higher fractions contain considerable amounts of aromatic and unsaturated hydrocarbons. 3. The formation of butane, hexanes, octanes, and other higher alkanes proceeds by the condensation of aliphatic diradicals having even numbers of carbon atoms with one another and subsequent hydrogenation. 4. The yield in the reaction is 16 molecules per 100 ev. 5. Reduction of the initial pressure raises the extent of the decomposition of ethylene without affecting the course of the reaction. Dilution of the ethylene with nitrogen considerably increases the degree of conversion with a sharp lowering of the yield of gaseous hydrocarbons. Dilution with hydrogen has almost no effect on the radiolysis of ethylene.
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  • 8
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1. With the aid of an automatic calorimeter having constant heat exchange and an adsorption apparatus with a capillary microburet, determinations were made of differential heats of adsorption and the adsorption isotherms for benzene vapor on carbon black, both graphitized and in its original oxidized state. Much of the surface of graphitized carbon is homogeneous and is filled at a constant heat of adsorption. The adsorption isotherm is satisfactorily described by the Langmuir and BET equations. 2. The relation of the free energy, total energy, and entropy of adsorption to the surface coverage was investigated. The respective standard values for adsorption of vapor and for wetting were determined. 3. A theoretical calculation of the adsorption energy of benzene was carried out by means of a summation of the dispersional interactions with the 100 nearest atoms of the graphite lattice, account being taken of interactions with the remaining atoms with the aid of an integral formula. The calculated value of the adsorption energy is very close to the measured heat of adsorption. 4. Comparison are made between the isotherms and heats of adsorption of benzene and hexane vapors. As requried by theoretical calculation, in the unimolecular region the heat of adsorption of benzene is considerably less than that of hexane.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 6 (1957), S. 241-243 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Adsorption energies of isolated atoms and simple nonpolar molecules on graphite were calculated on the basis solely of electric, magnetic, and geometric properties. The results of the theoretical calculation are in good agreement with experimental calorimetric data.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 8 (1959), S. 388-394 
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1. Using the electron-microscope method of carbon replicas, a study was made of the porous structure of a starting uniformly large-pored magnesium hydroxide sample, calcined at 200°, and of the magnesium oxide specimens obtained from it by calcination at 1000 and 1400°. 2. The skeleton of magnesium hydroxide has a corpuscular structure and is composed of plate-like crystallite. The plate-like character of the skeleton particles of the original magnesium hydroxide was still retained at calcination temperatures up to 1000°. Calcination at 1400° led to a pronounced sintering of the skeleton. 3. Based on electron-microscopic data, an estimate was made of the specific surface area and dimensions of the pores of both original specimen and after calcination at 1000°. The obtained results are found to be in harmony with those obtained earlier by the adsorption method.
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