Question

\[F{{e}_{3}}{{O}_{4}}\] is the chemical formula of:
(a) Monazite
(b) Magnetite
(c) Haematite
(d) bauxite

Answer 1

Hint: A chemical formula is the presentation of the chemical proportions of the constituent atoms that constitute a particular molecule or a compound. Some of the non-metal exist as simple molecules with two atoms joined together. These elements are diatomic.

Complete step by step answer:
\[F{{e}_{3}}{{O}_{4}}\] is an example of mixed oxide. It is a short notation for \[FeO.F{{e}_{2}}{{O}_{3}}\]. The name is derived from the name of its constituent oxides. FeO is called ferrous oxide while \[F{{e}_{2}}{{O}_{3}}\] is called ferric oxide. Hence, the name of compound ferrous ferric oxide. It is also known as magnetite.
It is also represented as Iron (II,III) oxide and is a black ore of iron which forms opaque crystals and exerts strong magnetism. They occur in nature in the form of mineral magnetite.
It is formed by a reaction called Schikorr reaction. The chemical reaction can be given as follows:
\[3Fe{{(OH)}_{2}}\,\to \,F{{e}_{3}}{{O}_{4}}\,+\,{{H}_{2}}\,+\,2{{H}_{2}}O\]

Iron forms both \[F{{e}^{2+}}\] and \[F{{e}^{3+}}\] ions. The first combines with oxygen ions to FeO; the second \[F{{e}_{2}}{{O}_{3}}\]. \[F{{e}_{3}}{{O}_{4}}\] can be thought of as a mixture of both compounds in equal amounts.
Let’s see why other options are incorrect.
a) Chemical formula of monazite \[(Ce,LA,Nd,Th)(PO_{4},SiO_{4})\], here any one cerium, lanthanum, neodymium, and thorium can substitute for the mineral's structure; and, we can also substitute silica for phosphate.
 c) Chemical formula for haematite is \[Fe_{2}O_{3}\].
 d) Chemical formula of bauxite is \[Al_{2}O_{3}.2H_{2}O\].

So, the correct option is (b).

Note: It is mainly used as a drug Ferumoxytol which is an iron replacement product indicated for the treatment of iron deficiency anemia in adult patients with chronic kidney disease.
It is also used in the water gas shift reaction as a catalyst in the “Haber process”.