“…In equilibrium, the monomer species, I or J (= A , B , C ), could form association complexes in the vapor or liquid phase, and the mixture could include monomers ( I 1 ), dimers ( I 2 ), and trimers ( I 3 ), which have been authenticated according to the aforementioned theoretical studies. As some examples of this behavior, ethanoic acid is considered to exist as a dimer and tetramer in the vapor phase, while the other group presumes that only dimer and trimer are formed . Moreover, homodimers, trimers, tetramers, and heterodimers were assumed to exist in the propanoic acid system, − and water exists in the forms of dimer, trimer, tetramer, and even higher polymers. − However, we have confirmed that not only monomer, homodimer, and homotrimer exist in the vapor and liquid phase but also heterodimerization occurs between two species I and J ( I ≠ J ), The maximum number of heterodimers M in the system of N components is given by Moreover, we have corroborated that heterotrimerization could take place between two species I and J ( I ≠ J ), No much higher complexes are verified according to the theoretical studies mentioned above. The maximum number of heterotrimers S in the system of N components is manifested similarly, The number of components found in the mixture could be different from the apparent N where the first, second, and third terms refer to all of the possible monomers, heterodimers, and heterotrimers, respectively.…”