Question

If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
(a) Do you think rust is different from iron?
(b) Can you change rust back into iron by some simple method.
(c) Do you think formation of rust from iron is a chemical change?
(d) Give two other examples of a similar type of change.

Answer 1

(a) Rust is hydrated iron oxide and it is not the same as iron.
(b) Rusting of iron leads to the transformation of iron into a new substance rust. It cannot be reversed by any simple method.
(c) Yes, rusting of iron is a chemical change. During the rusting of iron, it combines with oxygen in the presence of water (moisture) to form a new substance called rust. So, rusting of iron is a chemical change.
(d) Burning of paper and cooking of vegetables are two other examples of chemical change.