Question

Is tarnishing of silver useful or harmful chemical change

Answer 1

Tarnishing of silver is considered to be not useful. It is not considered useful because or else it would include regular polishing while tarnishing of silver shows significant chemical change.

This can be well understood by the redox reaction which includes the following equation:

Ag+2S = Ag2S

 Silver oxides and sulphides are further divided into solids in insoluble form and appears to be black in colour.

Answer 2

Chemical change

Explanation:

A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed. These are irreversible changes, which can't go back to its original state.

Tarnish: It is a method in which a metal is loosing luster, becoming dull or discolored.

Tarnishing usually happens in silver. It is a chemical change as in silver tarnishing process, it is chemically turning in Silver sulfide ($Ag_2S$). In this process, silver starts blackening as it starts changing color by loosing its luster and shine if left unprotected in humidity and atmospheric conditions.

As silver is widely used in making decoration items and jewellery. So, if it will loose shine , then it is harmful .