Question

Which of the following reactions does not take place during rusting?

• A. $H_{2}C{O}_3\rightleftharpoons 2H^{+}+C{O}_3^{2-}$
• B. $4F{e}^{2+}+O_{2\left(dry\right)}\to F{e}_2{O}_3$
• C. $4F{e}^{2+}+O_2+4H_{2}O\to 2F{e}_2{O}_3+8H^{+}$
• D. $F{e}_2{O}_3+x{H}_{2}O\to F{e}_2{O}_3\cdot x{H}_{2}O$

Answer 1

The correct option is B $4F{e}^{2+}+O_{2\left(dry\right)}\to F{e}_2{O}_3$

Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture.

The following redox reaction also occurs in the presence of water and is crucial to the formation of rust:

$4F{e}^{2+}+O_2\to 4F{e}^{3+}+2O^{2-}$

But in the given reaction $F{e}^{2+}$ is reacted with dry oxygen. And hence option B is wrong.

Various methods of prevention of rust are-

• Oiling - for example bicycle chains
  
• Greasing - for example nut and bolts
  
• Painting - for example car body panels
  
• Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc.