title: Significant discrepancies between van't Hoff and calorimetric enthalpies. II.
abstract: Isothermal calorimetric titration of 18-crown-6 ether with BaCl2 in pure aqueous solution over the temperature range 7-40 degrees C gives precise binding constants and enthalpy changes. Nonlinear least-squares fitting of the binding constants to the integrated van't Hoff equation, including a temperature-independent change in heat capacity, leads to van't Hoff enthalpies that differ significantly from the observed calorimetric enthalpies. This perplexing discrepancy appears at present to be very widely occurring.
authors.affiliation: Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: J M
authors.initials: JM
authors.lastname: Sturtevant
mesh_terms: D017609:Barium Compounds / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods*; D002712:Chlorides / Q000737:chemistry*; D043844:Crown Ethers; D004988:Ethers, Cyclic / Q000737:chemistry*; D008433:Mathematics; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D014867:Water
chemical_list: D017609:Barium Compounds; D002712:Chlorides; D043844:Crown Ethers; D004988:Ethers, Cyclic; D012996:Solutions; D014867:Water; C024986:barium chloride; C015762:18-crown-6