Question

is the chemical formula for iron oxide is FeO or Fe2O3.XH2O or Fe2O3​

Answer 1

Answer: Fe2O3​

AND, Fe2O3.XH2O (hydrated or rust)

Answer 2

The correct chemical formula for iron oxide is explained below.

• The formula of iron oxide is FeO and also known as ferric oxide.
• There are two conditions formed when the iron has two different valencies which are 2 and 3.
• When the iron has a valency of 2, then the formula becomes FeO because the valency of oxygen is two and cancels each other.
• When the iron has a valency of 3, then the formula becomes $Fe_{2}O_{3}$because the valency of oxygen is two and iron has a valency of three and cross valence each other.
• The hydrated formula of iron oxide is $Fe_{2}O_{3}.xH_{2}O$ which is rust and can have any number of water molecules.