These are not equal substances.
Fe3O4 is iron (II, III) oxide, also known as magnetite.
Fe is iron, a chemical element.
FeCl2 is iron (II) chloride, a compound containing iron in the +2 oxidation state.
FeCl3 is iron (III) chloride, a compound containing iron in the +3 oxidation state.
While they all contain iron as a common element, they are different compounds with different chemical properties.
These are not equal substances.
Fe3O4 is iron (II, III) oxide, also known as magnetite.
Fe is iron, a chemical element.
FeCl2 is iron (II) chloride, a compound containing iron in the +2 oxidation state.
FeCl3 is iron (III) chloride, a compound containing iron in the +3 oxidation state.
While they all contain iron as a common element, they are different compounds with different chemical properties.