This chemical sequence represents a series of reactions between sodium hydroxide (NaOH), iron hydroxide (Fe(OH)2, Fe(OH)3), iron oxide (Fe2O3), iron sulfate (Fe2(SO4)3), and barium sulfate (BaSO4). The reactions might proceed as follows:

NaOH + Fe(OH)2 -> NaFeO2 + H2ONaFeO2 + Fe(OH)3 -> Fe2O3 + NaOH + H2OFe2O3 + 3 H2O -> 2 Fe(OH)3Fe(OH)3 + 3 H2SO4 -> Fe2(SO4)3 + 3 H2OFe2(SO4)3 + 3 BaCl2 -> 2 FeCl3 + 3 BaSO4

In this reaction sequence, sodium hydroxide first reacts with iron hydroxide to form sodium iron oxide. Then, sodium iron oxide reacts with additional iron hydroxide to form iron oxide and regenerate sodium hydroxide. The iron oxide further reacts with water to form iron hydroxide, which reacts with sulfuric acid to form iron sulfate. Finally, the iron sulfate reacts with barium chloride to form iron chloride and barium sulfate.