Related Experiment Video
Updated: Jun 9, 2026

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Heats of formation of organic compounds by a simple calculation
Andreas A Zavitsas1, Donald W Rogers, Nikita Matsunaga
1Department of Chemistry and Biochemistry, Long Island University, Brooklyn, New York 11201, USA. zavitsas@liu.edu
Abstract:
Heats (enthalpies) of formation of organic compounds are obtained by adding a constant for a functional group to the heat of formation of its hydrocarbon precursor obtained by counting hydrogens, as previously described. A single molecule is used to obtain the contribution of each functional group. Unlike all other empirical schemes, no global fitting is used. The calculation is done with pencil and paper or a hand calculator. The accuracy of the results is demonstrated by their agreement with more than 360 species of experimentally known heats of formation with a mean average deviation of 0.75 kcal mol(-1), very nearly equal to the mean experimental uncertainty. Alcohols, hydroperoxides, ethers, amines, ketones, aldehydes, carboxylic acids, esters, chlorides, phenols, anilines, aryl ethers, nitriles, amides, and alkyl radicals are used as examples of the method. This success allows the calculation of experimentally unknown heats of formation. The method is limited to compounds that are not subject to strain or effects of conjugation. In such cases, the experimental heat of formation of the hydrocarbon precursor may be used. The method can be extended to functional groups not treated here.
More Related Videos
07:24Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer
Published on: February 19, 2018
09:38Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures
Published on: January 7, 2019
Related Concept Videos
Standard Enthalpy of Formation
Enthalpies of Reaction
Structure of Alkanes
Hydrocarbons are the simplest organic compounds composed of carbons and hydrogens. Based on the bond order between carbons, the hydrocarbons are further classified into alkanes, alkenes, and alkynes.
Alkanes are the simplest hydrocarbons with sp3 hybrid carbon atoms. These sp3...
Enthalpy and Heat of Reaction
What is Organic Chemistry?
Organic Compounds