Principle of Atom Conservation (POAC): This principle states that the moles of atoms of an element are conserved throughout the reaction. This means, moles of an element in reactants = moles of the element in products. eg. CO + O 2  -----> CO 2 In this moles of C in CO = moles of C in CO 2 This means, moles of CO = moles of CO 2 . Similarly, for O, moles of O in CO + moles of O in O 2  = moles of CO 2 Thus, moles of CO + 2(moles of O 2 ) = 2(moles of CO 2 )   Advantages of Mole Method over other Methods: (1) Balancing of chemical equations is not required in the majority of problems as the method of balancing the chemical equation is based on the principle of conservation of atom conservation.   (2) Number of reactions and their sequences, leading from reactants to products, need not be given.   Note: Whenever balanced chemical equation is given, mole method is very useful. eg. 2KClO 3  -----> 2KCl + 3O 2 Thus, 2(moles of KClO 3 ) = 2(moles of KCl)      3(moles of KClO 3 ) = 2(