Reactants → Products
A + B → AB
Condition Description Reaction or process is spontaneous in the forward direction Reaction or process is nonspontaneous (reaction is favored in the opposite direction) System is at equilibrium (there is no net change)
G = H – TS
|The three HT principles as listed on the HumanThermodynamics.com "principles" page in 2005. |
See main: HT principlesIn 2005, Libb Thims posted the adjacent set of general rules, classified as HT principles, something he has used as a philosophical guide since circa 2000, extrapolation of the above outlined spontaneity criterion into the language of crude or general rules to crouch one's choices upon, as reaction guides in times of confusion, so to say.  The following Pinterest poster seems to capture principle one: (Ѻ)
In 2012, Brazilian mechanical engineer, thermal scientist, and philosopher Mahesh Deva gave an in depth critique of the three HT principles.