Question

Why is zinc metal used for galvanization?
(A) Zinc get corroded easily than iron
(B) Zinc does not corrode
(C) Corrosion constant of iron increase
(D) All of the above

Answer 1

Hint: Zinc is a commonly used metal for galvanizing iron. Iron when exposed to the atmosphere reacts with the oxygen present and hence gets oxidized, this is how iron corrodes. A coating of zinc prevents the above reaction from happening.

Complete step by step answer:
Galvanization is the process of applying a protective zinc coating to iron, to prevent corrosion.
The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten hot zinc.
Galvanizing protects the underlying iron or steel in the following main ways:
-The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
-The zinc protects iron by corroding first. For better and long-term results, chromates along with zinc are used to galvanize iron.
-In the event the underlying metal becomes exposed, protection can continue as long as there is zinc close enough to be coupled electrically. Once the zinc in the area is consumed local corrosion of the base metal starts.
Hence from the above explanation we can conclude that zinc metal is used for galvanization as it prevents the corrosion of base metal (mainly iron) as zinc does not react with the oxygen present in the atmosphere and hence does not corrode.

So, the correct answer is “Option B”.

Note: Although galvanizing will prevent the attack of the base metal ( here, iron), corrosion is an inevitable phenomenon. After years of exposure, the metal will eventually start to corrode. For example, corrugated iron sheets used in roofs will start rusting in a few years. Galvanized iron exposed to the marine environment will start rusting as the zinc metal is converted to soluble zinc chloride which simply washes away.