Question

Why does a gold bar not corrode in moist air the way an iron bar does?

Answer 1

1. Corrosion is a natural process that transforms pure metals and waste into undesirable substances when they react with water or air, according to the definition. Corrosion damages the metal and spoils its physical appearance.
2. Metals generally corrode when they are attacked by external atmosphere such as air or moisture present in their surroundings, due to which all the atoms present on the surface of metal generally get oxidized and the surface of the metal gets damaged.
3. Generally, iron metals undergo corrosion because they react with the air and moisture in the atmosphere undergoing oxidation and forming hydrated iron (III) oxide which we call rust.
4. $\underset{\left(Iron\right)}{\underbrace{Fe\left(s\right)}}+\underset{\left(Oxygen\right)}{\underbrace{O_2\left(g\right)}}+\underset{\left(Moisture\right)}{\underbrace{x.H_{2}O}}\to \underset{\left(Rust\right)}{\underbrace{F{e}_2{O}_3.x{H}_{2}O}}$
5. The gold bar does not corrode in moist air because gold is a noble metal which means it does not react and does not undergo oxidation easily when it gets exposed to air and moisture present in the atmosphere. Gold is a very less reactive metal according to the reactivity series and it does not form a bond with oxygen easily.

Due to these reasons, we can say that the gold bar does not corrode in the same way as the iron bar does.