A Bordwell thermodynamic cycle use experimentally determined and reasonable estimates of Gibbs free energy (ΔG˚) values to determine unknown and experimentally inaccessible values.
[1][2] Analogous to Hess's law which deal with the summation of enthalpy (ΔH) values, Bordwell thermodynamic cycles deal with the summation of Gibbs free energy (ΔG) values.
The first more common component is that it refers to the physical conditions being at standard state.
The nought is assumed when working with equilibrium values such as Keq and pKa.
Its important to note that the fourth reaction in the series is an inverted homolytic bond cleavage stated in terms of free energy.