71 research outputs found
Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures
1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions,
enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration
structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These
interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However,
effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when
compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer
1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the
alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of
the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random
mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-alkanones. Steric effects and
cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of
temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and
support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project
FIS2010-1695
Die „Semesterberichte“ und die Entwicklung der Mathematikdidaktik in der Bundesrepublik Deutschland (1950–1980)
Beziehungen zwischen operativen “Programmen” in Mathematik, Psychologie und Mathematikdidaktik
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