Redox Potentials

The redox potential is a measure (in volts) of the affinity of a substance for electrons — its electronegativity — compared with hydrogen (which is set at 0).

Substances more strongly electronegative than (i.e., capable of oxidizing) hydrogen have positive redox potentials. Substances less electronegative than (i.e., capable of reducing) hydrogen have negative redox potentials.

Link to a discussion of electronegativity.

Oxidations and reductions

The Energy Relationships in Cellular Respiration and Photosynthesis: the Balance Sheet

The respiration (or burning) of a mole of glucose releases 686 kcal of energy. This value represents the difference between the energy needed to break the bonds of the reactants (glucose and oxygen) and the energy liberated when the bonds of the products (H2O and CO2) form.

Average bond energies, kcal/mole
C-H 98
O-H 110
C-C 80
C-O 78
H-H 103
C-N 65
O=O 116 (2