Rusting of iron is a chemical change because a new substance iron oxide is formed. The presence of oxygen and water or water vapour is essential for rusting. Rusting of iron is a continuous process which slowly eats up the iron objects and makes them useless.

Is rusting a physical change why?

A change in which one or more new substances are formed is known as chemical change. For Example, when the iron is exposed to air and moisture, rust formation takes place. Rust is nothing but Iron Oxide; a new substance formed out of the reaction. Hence, rusting of iron is a chemical change.

What chemical change is rusting?

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.