Intermolecular and Intramolecular Forces: A General Chemistry Laboratory Comparison of Hydrogen Bonding in Maleic and Fumaric Acids

• Frazier W. Nyasulu ^[1] ; John Macklin ^[1]
  1. [1] University of Washington

     University of Washington

     Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 83, Nº 5, 2006, pág. 770
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • This article presents a simple laboratory experiment that is designed to enhance students' understanding of inter- and intramolecular hydrogen bonding by demonstrating the comparative effect of these phenomena on some chemical and physical properties. Ball-and-stick molecular models are built and used for the consideration of hydrogen bonding possibilities in cis-1,2-dicarboxyethene (maleic acid) and trans-1,2-dicarboxyethene (fumaric acid). On the basis of the expected relative strengths of inter- and intramolecular hydrogen bond associations, students predict which of the two compounds has the higher melting point, higher first acid ionization constant, and higher second acid ionization constant. Appropriate measurements are then performed and used to identify which of a pair of compounds is maleic acid. Students are given standard enthalpies of sublimation, formation, combustion, and hydrogenation and asked to consider their relative values based on intra- and intermolecular hydrogen bonding.