Basic Thermodynamics


Many discussions of thermodynamics in undergraduate and even advanced textbooks are seriously lacking, with poorly considered concepts and even incorrect equations. We have started to set right some of these problems [J. Chem. Educ., 2014], showing that system work should generally be calculated as the volume integral of system pressure (rather than pext), and pointing out the implicit assumption of uniform pressure and temperature (uPT) processes underlying many equations in thermodynamics.

We have also provided the first explanation of the exothermicity of all combustion reactions, showing why fire is hot regardless of the composition of the fuel and predicting the heat of combustion (-418 kJ/mol times the number of moles of O2) from the elemental composition with an uncertainty of only a few percent. Our analysis overturns some conventional notions of the energetics of molecules, for instance that the heat of combustion arises from breaking high-energy bonds in the fuel, and reveals that CO2 has essentially the same total bond energy as CH4. [J. Chem. Educ., 2015]


  1. Klaus Schmidt-Rohr "Why Combustions Are Always Exothermic, Yielding About 418 kJ per Mole of O2" J. Chem. Educ., 92: 2094-2099 (2015).
  2. Klaus Schmidt-Rohr "Expansion Work without the External Pressure, and Thermodynamics in Terms of Quasistatic Irreversible Processes" J. Chem. Educ. 91: 402-409 (2014).