Integrated SequencePhysics Chemistry Organic Biology

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Chem1 Virtual Textbook - Thermochemistry and calorimetry
Good introduction to the use of enthalpy of formation along with Hess' Law of Heat Summation in thermochemistry problem solving.

Chem1 Virtual Textbook - Some applications of enthalpy and the First Law
Applying the logic of Hess' Law in various contexts.

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Special points of emphasis


Chemical Thermodynamics and the Equilibrium State

Chemical Kinetics



Bioenergetics and Cellular Respiration

Hess's Law of Heat Summation is a correlative of the more general proposition that changes in the thermodynamic functions describing a chemical system do not depend on the reaction pathway but on the initial and final states of the system. This is very helpful for understanding the changes of oxidative metabolism, which are extremely complex in path, but simple stoichiometrically.

The oxidation of nutrient molecules (glucose, triglyceride, etc) to CO2 and H2O produces the same internal energy change, enthalpy change, or free energy change whether by combustion in the laboratory or through the metabolic pathway.

An important related proposition is that enzymes accelerate the rate of a chemical reaction but do not change the position of equilibrium. A catalyst can change the reaction pathway but not the overall thermodynamics. While the kinetics of a reaction depend on the path, the chemical thermodynamics do not.

Almost every MCAT will have some question to see if you can comfortably separate kinetic (path dependent) reasoning from thermodynamic (path independent) reasoning.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

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