A differential thermal analysis study of the system lead(II) dodecanoate/dodecanoic acid

Data are presented for the heats and entropies of phase changes for the system lead(II) dodecanoate/dodecanoic acid. A phase diagram has also been constructed for the system. Optical observations using a hot-stage polarising microscope suggest that in mixtures containing very low acid concentration...

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Bibliographic Details
Published in:Thermochimica acta 1978-01, Vol.27 (1), p.133-140
Main Authors: Adeosun, S.Oluyemi, Akanni, M.Shola
Format: Article
Language:English
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Summary:Data are presented for the heats and entropies of phase changes for the system lead(II) dodecanoate/dodecanoic acid. A phase diagram has also been constructed for the system. Optical observations using a hot-stage polarising microscope suggest that in mixtures containing very low acid concentration ( X acid⩽ 0.01), the is the same as in the pure soap, i.e. crystal → G isometric → V 2 isomorphorous → liquid. The V 2 phase disappears at higher acid concentrations. At high acid concentrations ( X acid ⩾ 0.06) a new phase transition occurs at temperatures very close to the melting point of the pure acid. The total entropy change accompanying the transformation crystal → liquid phase is the same for all the compositions studied. This suggests that the addition of dodecanoic acid to lead dedecanoate does not alter the degree of order of the hydrocarbon chains either in the solid or liquid phase.
ISSN:0040-6031
1872-762X
DOI:10.1016/0040-6031(78)85027-8