Question

17. If you leave a piece of iron in the open for a few days in coastal areas, it acquires a film of
brownish substance, called rust.
(a) How is rust formed?
(b) Why can't you change rust back into iron?
(c) Do you think formation of rust weakens iron?
(d) Give two other examples of a similar type of change.​

Answer 1

Answer:

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a piece of iron in the open for a few days in coastal areas, it acquires a film of

brownish substance, called rust.

Answer 2

Answer:

a piece of iron in the open for a few days in coastal areas, it acquires a film of  brownish substance, called rust.

a.)Rusting is an oxidation reaction. The iron reacts with water and oxygen to form hydrated iron(III) oxide, which we see as rust. Iron and steel rust when they come into contact with water and oxygen – both are needed for rusting to occur.

b.)No rusting of iron is a chemical change because in this reaction a new substance,rust (iron oxide) is formed.It can't be reversed by any simple method.

c.) Rusting causes iron to become flaky and weak, degrading its strength, appearance and permeability. Rusted iron does not hold the desirable properties of iron. The rusting of iron can lead to damage to automobiles, railings, grills, and many other iron structures.

d.) Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding.

Explanation:

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