Question

Which of the following methods is suitable for preventing an iron frying pan from rusting?
(A) Applying grease
(B) Applying paint
(C) Applying a coating of zinc
(D) All of the above

Answer 1

Hint: We need to find a method by which we can prevent the iron of the pan from coming in direct contact with water and atmospheric oxygen. The method should also be a practical solution to the problem.

Complete step by step solution:
We will get information about the methods to prevent a frying pan from rusting.
- We know that rusting is a process which occurs when metals like iron come in direct contact with atmospheric oxygen. Water in the atmosphere catalyzes that reaction. Thus, the overall reaction is the oxidation of iron metal with oxygen. So, we can say that following reaction occurs
\[F{e_{(s)}} \to F{e^{2 + }} \to F{e^{3 + }}\]
- Now, in order to stop this oxidation process, we need to make sure that the iron metal does not come in direct contact with water or oxygen. One of the easiest ways is to put some cover on it that prevents the iron from coming in direct contact with oxidizing agents.
- Galvanization is the process in which we form a layer of a metal like zinc so that iron metal gets covered. Zinc is cheap and adheres well enough to iron. It also provides cathodic protection to the iron surface in case of damage to the zinc layer.
- If we apply paint or grease on an iron pan, we can surely prevent iron from coming in direct contact with oxidizing agents but these methods are not practical as we may use the pan frequently and both grease and paint cannot survive heat and cleaning processes. In the end we see that these methods are not suitable.
- Thus, we can conclude that applying a coating of zinc is the best way to prevent an iron frying pan from rusting.

So, the correct answer is (C).

Note: In modern days aluminum is added to the zinc layer and it makes the layer last for a longer period of time. Typically, for day-to-day use products, the layer of zinc is less than $100$$\mu m$ thick.