Question

Wrote the name of compound formed during corrosion of following metal 1. Iron 2.copper 3.silver

Answer 1

Hey.

Here is the answer.

1. Reddish brown flaky substance, known as rust, is formed on its surface. Rust is chemically hydrated iron (lll) oxide, Fe2O3.xH2O.

2. The metal Copper corrodes in a very negligible manner . Copper lies ranks very low in electrochemical series and has an inertia towards corrosion. But given suitable conditions like presence of oxides, carbon-dioxides, sulphur bearing compounds , it slowly corrodes on the surface giving a dark colour which gradually changes in to green. It is primarily due to formation of chlorides, sulphates, sulphides of the metal. Unlike Iron its topmost layer acts as protective cover to the underlying metal. The coating on the metal is often patina. 

3. Noble metals like silver also corrode in presence of some chemical compounds like Hydrogen Sulphide. This process is called tarnishing . It often appears as a dull, gray or black film or coating over metal. Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the metal react, and the layer of tarnish seals and protects the underlying layers from reacting. Silver tarnish is usually comprised of Ag2O or Silver(I) oxide which gives a darker color to the metal.

Thanks.