Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/95693
Type: Artigo de periódico
Title: Determination Of The Mean Enthalpy Of Dissociation Of Arsenic-oxygen Bonds In Some Arsenic (iii) Alkoxides
Author: De Souza A.G.
Brasilino M.G.A.
Airoldi C.
Abstract: The standard molar enthalpy of formation of arsenic alkoxides in the liquid phase, As(OR)3 {R = ethyl (Et), n-propyl (Prn), i-propyl (Pri), n-butyl (Bun), and i-butyl (Bui)}, was determined through reaction-solution calorimetry in chloroform based on the reaction: As(NEt2)3(1) + 3ROH(1) = As(OR)3(1); ΔsolHmo at T = 298.15 K. This series of alkoxides gave the following molar enthalpy of formation ΔfHmo values: -(758.1 ± 9.0) kJ · mol-1, -(774.3 ± 9.0) kJ · mol-1, -(809.8 ± 9.0) kJ · mol-1, -(828.8 ± 8.9) kJ · mol-1, and -(863.4 ± 8.9) KJ · mol-1, respectively. The standard molar enthalpies of vaporization ΔvapHm (47.9 ± 1.1) kJ · mol-1, (51.2 ± 1.8) kJ · mol-1, (80.1 + 0.9) kJ · mol-1, (64.0 ± 1.8) kJ · mol-1 and (75.7 ± 1.2) kJ · mol-1, were obtained for the same sequence of alkoxides, by means of differential scanning calorimetry. By combining the preceding values with the standard molar enthalpy of formation of the alkoxide ΔfHm in the liquid phase, the standard molar enthalpy of formation of these compounds in the gas phase was obtained as -(710.2 ± 9.0) kJ · mol-1, -(723.1 ± 9.1) kJ · mol-1, -(729.3 ± 9.0) kJ · mol-1, -(764.8 ± 9.1) kJ · mol-1, and -(787.7 ± 9.0) kJ · mol-1, respectively. From these values, the mean enthalpy of dissociation of the arsenic-oxygen bond 〈Dm〉(As-O) was calculated for the sequence of the above alkoxides to give: (320 ± 5) kJ · mol-1, (301 ± 5) kJ · mol-1, (292 ± S) kJ · mol-1, (293 ± 5) kJ · mol-1, and (294 ± 5) kJ · mol-1. The linear correlation between the standard molar enthalpies of formation of the liquid alkoxides ΔfHm{As(OR)3,1} and the respective alcohol ΔfHm(ROH,1), suggests that these thermochemical data can be assessed for a series of normal and iso chain alcohols. © 1996 Academic Press Limited.
Editor: 
Rights: fechado
Identifier DOI: 10.1006/jcht.1996.0118
Address: http://www.scopus.com/inward/record.url?eid=2-s2.0-0039584800&partnerID=40&md5=062974b9445247880003e6be91086b34
Date Issue: 1996
Appears in Collections:Unicamp - Artigos e Outros Documentos

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