David L. Wertz

Drying of Beulah-Zap Lignite

Abstract Lignite dried in a stream of dry nitrogen at moderate temperatures (20–80 °C) loses water in two distinguishable modes. The first mode represents about 80–85% of the loss of moisture. The second represents the other 15–20% lost under these conditions. The rate follows a unimolecular mechanism (like radioactive decay) for each mode. The activation energy for the first mode is close to the heat of vaporization of water. The rate is dependent upon the gas flow around the sample and the weight (or thickness) of the sample. Work at Amoco Oil Company indicated that the oil yield was higher for the dried coal than for raw or partly dried lignite. Work at Southern Illinois University showed that the mechanism was the same when differential scanning calorimetry was used to follow the kinetics of drying. Other work at the University of Southern Mississippi showed that the physical structure of the lignite (measured by X-ray diffraction) is measurably different for the dried and raw materials.

X-ray diffraction study of some concentrated cobalt /II/ chloride solutions.

Diffraction results, interpreted in light of colligative measurements, indicate that the environment of Co(II) differs drastically when CoCl2 is dissolved in water and in alcohols. In H2O, the predominant cation species is Co (H2O)62+ with the Co–O distance being about 2.1 A. In methanol and ethanol, the solute species is highly associated and each Co(II) has four chloride nearest neighbors at about 2.30 A. The relative co‐ordinating abilities of the potential ligands towards Co(II) are H2O > Cl− > CH3OH≃C2H5OH. Crystal radii serve to interpret bond distances.

On the coordination of La3+ in aqueous LaBr3 solutions

Abstract The structure of the average solute species in two concentrated aqueous LaBr 3 solutions has been measured. In each solution La 3+ has 8.0 (± 0.2) nearest oxygen neighbors and several outer-sphere bromide neighbors. The average LaO nearest neighbor distance is 2.48 A and the ion-paired La ⋯ Br distance is 4.8 A.

Solute species and equilibria in concentrated zinc chloride/hydrochloric acid solutions☆

Abstract Examination of a series of concentrated ZnCl2HClH2O solutions with chloride/zinc stoichiometries ranging from 2:1 to 6:1 and with the mole fraction of Zn2+ being 0·015 in each solution have been examined by X-ray diffraction. The mean coordination of Zn2+ in each solution is pseudotetrahedral with the ZnCl and ZnO contact distances being 2·30 and 2·05 A, respectively. The average number of chlorides tightly bonded to Zn2+ is, as expected, significantly related to the chloride/zinc and/or the chloride/water stoichiometries. The formation constant for tetrachlorozincate (II) in these solutions is ca. 80 M−2 if it is assumed that tetrachlorozincate(II) and/or dichlorodiaquozinc(II) are the principal species in each of these solutions.

Effect of Molecular Structure on Mesomorphism.11.1 A Siamese Twin Liquid Crystal Having Two Independently Smectogenic Conformations

Abstract Two different molecular conformations of a particular Siamese Twin liquid crystal can, independent of each other, give rise to a smectic C phase. X-ray diffraction results are presented from which it is concluded that there are two possible conformations of this molecule in the solid state and that different smectic C layer types can be formed by melting these different solid state conformations.

On the existence of pseudo-tetrahedral tetrachlorozincate(II) in hydrochloric acid solutions☆

Abstract We have examined two solutions of zinc chloride dissolved in hydrochloric acid with mole fractions of Zn2+ of 0·015 and 0·019 and with chloride/zinc solution stoichiometries of ca. 6:1 by X-ray diffraction. Our results, coupled with Raman spectra/analysis previously published, establish that the predominant species in these solutions is ZnCl42− where the coordination of Zn2+ is at least near-tetrahedral. The mean ZnCl distance is 2·30 A. Non-bonded interactions between tightly coordinated chlorides occur at ( 8 3 ) 1 2 × 2· 30 A .

One-dimensional description of the average polycyclic aromatic unit in Pocahontas No. 3 coal: an X-ray scattering study

Abstract The radial distribution method was used to examine the non-crystalline portion of a low-volatile bituminous coal, Pocahontas No. 3, from Buchanan County, VA, USA. This coal, one of the Argonne Premium Coal Sample Program, was used as received for X-ray absorption/diffraction/scattering experiments. The diffraction due to the crystalline minerals contained in the coal and due to the graphene layering peak was removed from the amorphous scattering component. The latter was fitted to the self-scattering curve constructed from the scattering factor for carbon and the difference was Fourier transformed to obtain the one-dimensional structural details of the average short-range structural unit in this coal. Interpretation of the radial distribution indicates that the average structural unit is ∼ 80% aromatic and consists of polycyclic six-membered rings which are predominantly, if not exclusively, planar. In addition, the average graphene layer has a diameter of ∼ 7.7 A. The radial distribution function results compare favourably with those obtained by 13 C NMR spectroscopy.

Structure of Iron (III) Chloride–Methanol Solutions

The structure of the solute species in concentrated iron(III) chloride–methanol solutions has been examined by diffraction techniques. Solute association is established by colligative measurements and indirectly by diffraction results and Fe2Cl6 emerges as a realistic solute species. The radial‐distribution functions of the solutions and those obtained from electron diffraction studies of vapor‐phase Fe2Cl6 are comparable. The average iron(III)–chloride bond distance is 2.25 A, and each iron atom has four chloride nearest neighbors; both facts are consistent with the dimer model. Crystal radii serve to interpret bond distances.

X-ray scattering analysis of the average poly-cyclic aromatic unit in argonne premium coal 401

Abstract An X-ray scattering study of APC 401 (a coal taken from the Pittsburgh seam), using MoK α X-rays, indicates that the longest distance between carbon atoms in the mean poly-cyclic aromatic (PCA) unit is approx. 7.5 A. The radial-distribution function indicates that, on the average, each carbon 2.2 nearest carbon neighbors at an average distance of 1.43 A. This information is consistent with the interpretation that 27% of the CC bonds in this coal involve at least one alkyl carbon, while 73% of the CC bonds are between aryl carbons. Comparisons of the atom-pair correlation function to simulated one-dimensional structure functions calculated from three-dimensional structural models of several poly-cyclic molecules indicate that a ribbon-shaped C 14 unit (analogous to anthracene) best agrees with the results of our X-ray scattering data. Interpretation of the atom-pair correlation function also suggests that the alkyl carbons are predominantly, if not exclusively, bonded to the PCA unit.

The coordination of Cu(II) in a nearly saturated solution of CuCl2 in hydrochloric acid

Abstract Via X-ray diffraction the mean solute species in a very concentrated solution of CuCl 2 HClH 2 O has been measured. The coordination of Cu(II) in this nearly saturated solution is distorted octahedral. The average solute species is best described as Cu 4 Cl 10 (H 2 O) 8 where chlorides occupying both axial and equatorial coordination sites about Cu(II) function as bridging ligands. The coordination of Cu(II) in this solution is similar to that found in very concentrated aqueous solutions and in crystalline CuCl 2 . 2H 2 O. Based upon interpretation of the atomic radial-distribution function the average CuO eq distance, the average CuCl eq distance, and the average CuCl ax distance have been calculated to be 1·95, 2·27 and 2·6A, respectively.