Question

Complete the process of iron rusting by filling the blanks. Suggest a way to prohibit the process.
The iron rust is formed due to........................... reaction. Different
regions on iron surface become anode and cathode.
 Reaction on anode region :

`F_e(s) → Fe^(2+) (aq) +2e^-`

 Reaction on anode region :

`O_2(g) + 4H^+(aq) +............................ → 2H_2 O (l) `

When Fe²⁺ ions migrate from anode region they react with ................... to form Fe³⁺ ions.
A reddish coloured hydrated oxide is formed from ............... ions. It is called rust.

`2Fe_(3+) (aq) + 4H_2O(l) → ................. + 6H_+(aq) `

A way to prevent rusting ..................................................................

 

 

Answer 1

The iron rust is formed due to Electrochemical reaction. Different  regions on iron surface become anode and cathode.
 Reaction on anode region :

`F_e(s) → Fe^(2+) (aq) +2e^-`

 Reaction on anode region :

`O_2(g) + 4H^+(aq) + 4 e-  → 2H_2 O (l) `

When Fe²⁺ ions migrate from anode region they react with water  to form Fe³⁺ ions.
A reddish coloured hydrated oxide is formed from Fe³⁺  ions. It is called rust.

`2Fe_(3+) (aq) + 4H_2O(l) → Fe_2O_3 . H_2O(s) + 6H_+(aq) `

A way to prevent rusting (Marks should be given for complete process and correct answers)
Prevention by colouring with acrylic paints, Zn plating, galvanizing, anodizing, alloying etc.) (Any one way of prevention expected.)