= =>LEAST COMPLEX
 
*CHEMICAL RATE LIMITED
(1)    Simple Kinetic Theory of bimolecular reactions: reaction rate coefficient equals the  collision frequency.
 
(2) Modified Kinetic Theory: reaction rate coefficient equals,
      collision frequency x activation energy factor x steric factor
 
(3) a. Transition State Theory (TST): unimolecular/bimolecular reactions
         Rate coefficient includes an activation energy factor, and an entropy factor to
account for steric effect.
      b. Lindemann theory of unimolecular reactions.
 
 
*ENERGY TRANSFER LIMITED.
 
Quantum mechanical treatment of thermal activation, and
unimolecular/bimolecular chemical activation. Rate coefficients depend on the Internal energy of molecular species.
 
= =>MOST COMPLEX
Table 2: Theories for estimating reaction rate coefficients.