Abstract
ABSTRACTOne aim of this work was to measure the activity of water and aroma compounds in aqueous solutions simultaneously.The volatilities of aroma substances at infinite dilution in aqueous solutions of polyethylene‐glycols (PEG) were studied. the activity coefficients (γi∞) of volatile compounds were measured by gas stripping (exponential dilution). This dynamic method also allowed the measurement of the water activity of these solutions. the results showed that: the influence of polyethylene‐glycols on γi∞ depended most strongly on the PEG mass fraction in the solution. the effect of the PEG molecular weight was not significant. γi∞ increased as molecular weight and length increased for the homologous series of alcohols tested. This can be explained by entropic effects. Probably, the same effect occurs for other homologous series. γi∞ for 2‐propanone increased as temperature increased. Based on this relation, molar partial excess enthalpies of mixing were calculated for 2‐propanone in an aqueous solution.
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