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|Title:||Studies on complexation between urea and 18-crown-6 in aqueous solutions at 298.15K|
|Abstract:||<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> Osmotic vapor pressure and density measurements have been made for binary aqueous urea solutions (0.1<i style="">m</i>-1<i style="">m</i>) and ternary aqueous solutions containing three different concentrations of 18-crown-6 (0.1, 0.2 and 0.5<i style="">m</i>) at 298.15K. The molal activity coefficients of urea, water and 18-crown-6 in binary as well as in ternary solutions have been calculated. Thermodynamic equilibrium constant, salting coefficient and molecular interaction parameters have been determined. The results are explained in terms of 1:4 stoichiometric complex formation with urea at the lowest concentration of 18-crown-6 having a small equilibrium constant value. At higher 18-crown-6 concentrations, water forms hydrogen bond with crown ring oxygen atoms and hydrophobic interaction between 18-crown-6 molecules outweighs the interaction of urea with 18-crown-6 molecules, resulting in salting out of urea molecules. </smarttagtype>|
|Appears in Collections:||IJC-A Vol.48A(09) [September 2009]|
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