Question

Rust is a mixture of
A.$FeO$ and $Fe{\left( {OH} \right)_2}$
B.$FeO$ and $Fe{\left( {OH} \right)_3}$
C.$F{e_2}{O_3}$ and $Fe{\left( {OH} \right)_3}$
D.$F{e_3}{O_4}$ and $Fe{\left( {OH} \right)_3}$

Answer 1

Hint: We also know that when iron and moist air comes together, they react with each other and form a brown coloured powder known as rust. It is produced from a redox reaction having oxygen and iron present in an environment that has water. Not all oxides of iron are rust.

Complete step by step solution:
We have to remember that the rust is an iron oxide. It appears as reddish brown oxide which is formed by the reaction of iron and oxygen in the presence of water or air moisture. As we know that the rust also is seen in several other colors like yellow, green and brown. The several chemical compositions of rust are given by reflection of various colours.
We must remember that the rust is formed when iron (or) alloys of iron contacts in comes with moist air. The oxygen and water present in the air reacts with metal to yield hydrated oxide.
Rusting of iron has the the formation of hydrated oxide, $Fe{\left( {OH} \right)_3}$, $FeO\left( {OH} \right)$ or even \[F{e_2}{O_3}\cdot{H_2}O\]. It is an electrochemical process which needs the presence of water, oxygen and an electrolyte. In the absence of any one substance of these the process of rusting does not take place to any great extent.
We have to remember that the rust has hydrated iron(III) oxides \[F{e_2}{O_3}\cdot{H_2}O\] and iron(III) oxide-hydroxide$F{e_2}{O_3}$ and $Fe{\left( {OH} \right)_3}$. It is associated with the corrosion of refined iron.
Therefore, the option (C) is correct.

Note:We have to remember that pure iron oxide isn’t rust, only iron oxide hydrate is rust. The common red form of rust is $F{e_2}{O_3}$ whereas iron shows several oxidation states, thus it could give rise to other colors of rust. Dry air does not cause rusting. Rusting is an example of corrosion and electrochemical reaction.