Strain Energy in Organic Compounds: Bomb Calorimetry

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Strain Energy in Organic Compounds: Bomb Calorimetry by Andrew J. Meyer, Jeremy M. Brunette, and Franklin Chen, Department of Chemistry, University of Wisconsin–Green Bay, Green Bay, Wisconsin 54311; [email protected] Keywords: Upper-Division Undergraduate, Physical Chemistry, Organic Chemistry, Inquiry-Based/Discovery Learning, Thermodynamics, Calorimetry/Thermochemistry

This exercise outlines a guided, data-driven method in which physical chemistry students can learn about bomb

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edited by

W. Tandy Grubbs Stetson University DeLand, FL 32720

calorimetry calculations and how such measurements may yield information about the relative strain energy of selected compounds. Two organic compounds of the same empirical formula but different molecular formulas were used for this investigation: 1,4-cyclohexanedicarboxylic acid, which has a six-membered ring, and cyclopropanecarboxylic acid, which has a three-membered ring. The molar mass of the six-ring compound is exactly twice that of the three-ring compound. The results indicate that the heat of combustion of 1,4-cyclohexanedicarboxylic acid is less than twice that of cyclopropanecarboxylic acid. This difference is ascribed to the strain energy difference between a six-membered ring and a three-membered ring.

Journal of Chemical Education  •  Vol. 86  No. 6  June 2009  •  www.JCE.DivCHED.org  •  © Division of Chemical Education