Question

What is the correct name of ${\rm{FeO}}$?

A. Iron (I) oxide
B. Iron oxide
C. Iron (II) oxide
D. Iron monoxide

Answer 1

Hint: We know that, name of a chemical compound is given using the name and oxidation state of the cation and anion of the compound. Iron is a metal and it has exhibited two oxidation states namely +2 and +3.

Complete step by step answer: First we understand how to write the chemical formula of a compound. To write the chemical formula of a compound, first we have to write the chemical symbols of the elements along with the valency then, we have to crossover the valencies of the combining elements. For example, formula is written from aluminium oxide.

So, the formula of aluminium oxide is ${\rm{A}}{{\rm{l}}_2}{{\rm{O}}_{\rm{3}}}$

Let’s identify the correct answer from the options.

Option A says the name of FeO is Iron (I) oxide .The name Iron (I) oxide indicates that valency of iron is +1 and we know valency of oxide is -2. So, the formula is${\rm{F}}{{\rm{e}}_2}{\rm{O}}$. So, A is incorrect.

Option B says the name of FeO is iron oxide. We know another name of iron oxide is Iron (III) oxide. This indicates that, valency of iron is 3+ and that of oxide is 2-.So, the chemical formula of iron oxide is ${\rm{F}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}$. So, option B is incorrect.

Option C says the iron name of FeO is iron (II) oxide. But, Iron (II) oxide indicates, the valency of iron is 2+ and that of oxygen is 2-. So, the formula for Iron (II) oxide is FeO.
Hence, option C is the correct answer.


Note: In naming of iron oxide, always remember that, if the iron atom possesses +2 oxidation state, the oxide is ferrous oxide $\left( {{\rm{FeO}}} \right)$ and if the iron atom possesses +3 oxidation state, the name of the iron oxide is ferric oxide $\left( {{\rm{F}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}} \right)$.