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2001 (1)
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1Author    H. Oppermann, H. Dao Quoc, M. Zhang-PreßeRequires cookie*
 Title    Thermical and Calorical Behaviour of Solid LaAl3Br12 and Chemical Transport of LaBr3 with AlBr3  
 Abstract    The thermodynamical data of solid Lanthanum Aluminium Bromide LaAl3 Br12 have been obtained by determination of the decomposition equilibria from total pressure measurements. For different compositions LaBr3 /AlBr3, the barogram of the binary system LaBr3 -AlBr3 was constructed and from this and DTA the melting diagram was determined. The chemical trans­ port of LaBr3 with AlBr3 is suggesting the existence of two gaseous complexes LaAl3 B r12 and LaAl?Br9. The data are: Z\H°B(LaAl3B rl2,f,298) = -587,2 ± 7 kcal/mol, S°(LaAl3Br12,f,298) = 179,3 ± 7 cal/Kmol; zAH°B(LaAl3B r12,g,298) = -548,7 ± 5 kcal/mol, S°(LaAl,Br12,g,298) = 239,4 ± 6 cal/K mol; Z\H°B(LaAl2Br9,g,298) = -619,7 ± 5,5 kcal/mol, S°(LaAl2Br9,g,298) = 212,0 ± 7 cal/K mol. From solution calorimetric measurements follows the enthalpy of formation of the solid com­ plexes: zAH°B(LaAl3Br12,f,298) = -590,9 ± 3 kcal/mol. Thermisches und kalorisches Verhalten von festem LaAl3Br12 
  Reference    Z. Naturforsch. 56b, 908—916 (2001); eingegangen am 10. Mai 2001 
  Published    2001 
  Keywords    Lanthanum Alumimium Bromide, Calorimetry, Enthalpy 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-0908.pdf 
 Identifier    ZNB-2001-56b-0908 
 Volume    56 
2Author    BoźennaR. Óźycka-Roszak, Romuald Żyłka, Janusz SarapukRequires cookie*
 Title    Hydration of Alkylammonium Salt Micelles -Influence of Bromide and Chloride Counterions  
 Abstract    Fax: (+48)-71 -2 0 5 -1 7 2 . E-mail: BO RO @ozi.ar.w roc.pl The micellization process of dodecyltrimethylammonium chloride (D TA C) and bromide (D T A B) was studied. N uclear magnetic resonance method was used. The 'H N M R and 13C N M R spectra were taken at higher and lower concentrations than the critical micelle concentrations (CM C) of the compounds studied. Chemical shifts were analysed. The studies perform ed were prompted by earlier calorim etric measurements which showed that there were significant qualitative and quantitative differences in the micellization process of the compounds studied. Namely, D T A B micelle dissociation was found to be an endothermic process while that of DTA C was exothermic. The differences found must be the result of differentiated influence of bromide and chloride counterions on the micellization process, including the phenomenon of micelle hydration. The objective of the work was to check whether cationic surfactant counterions can influence the micelle hydration process. Indeed, D TA B and D TAC, as monomers, exhibit similar hydrophobic hydration, but D TA B micelles are m ore hydrated than D TA C ones. It seems that the differences found in micellization of both salts studied may be attributed to different physicochemical properties of bromide and chloride ions, such as their mobilities and radii of their hydrated forms. M oreover, the effect of anions on the water structure must be taken into account. It is important whether the anions can be classified as water ordering kosmotropes, that hold the first hydration shell tightly, or water disordering chaotropes, that hold water molecules in that shell loosely. 
  Reference    Z. Naturforsch. 55c, 413 (2000); received January 10/March 6 2000 
  Published    2000 
  Keywords    Micelle Hydration, Calorimetry, Counterions 
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 TEI-XML for    default:Reihe_C/55/ZNC-2000-55c-0413.pdf 
 Identifier    ZNC-2000-55c-0413 
 Volume    55 
3Author    U. Petasch, C. Hennig, H. OppermannRequires cookie*
 Abstract    n te r s u c h u n g e n z u m q u a s ib in ä r e n S y s te m B i2T e3 /B iC l3 Investigations on the Pseudobinary System Bi2Te3/BiCl3 The phase diagram of the pseudobinary sytem Bi2Te3/BiCl3 was investigated by DTA, total pressure measurements, and X-ray phase analysis. Only BiTeCl exists as a ternary phase in this system. The compound melts incongruently at 430 °C. The heat of formation and the standard entropy of BiTeCl were calculated from vapor pressure data: AH°b (BiTeCl, f, 298) = (-39,5 ± 1,6) kcal/mol; S° (BiTeCl, f, 298) = (34,4 ± 2,7) cal/K mol. The heat of formation of BiCl3 was determined on the basis of the heat of solution of BiCl3 and Bi20 3, and the heat of formation of Bi20 3: z\Hß (BiCl3, f, 298) = (-95,9 ± 0,9) kcal/mol. 
  Reference    Z. Naturforsch. 54b, 234—238 (1999); eingegangen am 9. Oktober 1998 
  Published    1999 
  Keywords    Bismuth Telluride Chloride, Phase Diagram, Total Pressure Measurements, Calorimetry, Thermodynamic Data 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0234.pdf 
 Identifier    ZNB-1999-54b-0234 
 Volume    54