(m ≤ n) may form during synthesis of M, where A i and b j i are the i th chemical species and stoichiometry, respectively, of the j th competing compound. It is more favorable for C j than M to form when C j 's enthalpy of formation, ∆H f C j , is more negative than ∆H f M . Equivalently, M is stable when the formation enthalpy of each competing compound satisfies