Thermodynamics of fenoxycarb in solution

Manuel Kuhs, Michael Svärd, Åke C. Rasmuson

Research output: Contribution to journalArticlepeer-review

Abstract

The solubility of fenoxycarb has been determined between 278 and 318 K in several organic solvents. The solid phase at equilibrium and some indication of polymorphism has been properly examined by powder XRD, DSC, Raman and ATR-FTIR spectroscopy, solution 1H NMR and SEM. Using literature data the activity of the solid phase within a Raoult's law definition has been calculated, based on which solution activity coefficients have been estimated. In ethyl acetate, the van't Hoff enthalpy of solution is constant over the temperature range and equals the melting enthalpy. However, it is shown that the solution is slightly non-ideal with the heat capacity difference term compensating for the activity coefficient term. In toluene, the van't Hoff enthalpy of solution is constant as well but clearly higher than the melting enthalpy. In methanol, ethanol and isopropanol, van Hoff curves are strongly non-linear, the slope however clearly approaching the melting enthalpy at higher temperatures. In all solvents, positive deviations from Raoult's law are prevailing. The activity coefficients follow a decreasing order of isopropanol > ethanol > methanol > toluene > ethyl acetate, and in all solvents decrease monotonically with increasing temperature. The highest activity coefficient is about 18 corresponding to about 2.5 kJ/mol of deviation from ideality.

Original languageEnglish
Pages (from-to)50-58
Number of pages9
JournalJournal of Chemical Thermodynamics
Volume66
DOIs
Publication statusPublished - 2013

Keywords

  • Activity
  • Activity coefficient
  • Heat capacity
  • Hoff enthalpy
  • Ideal solution
  • Solubility
  • Van't

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