Question

Why do silver article turn black?Name the phenomenon?Name the black substance and its chemical formulae?

Answer 1

A silver article turns black when kept in the open for a few days.It happens because exposure of air causes it to form silver sulphide with the reaction of oxygen and hydrogen sulphide gas present in atmosphere which makes the silver metal turn black.

This phenomenon is called tarnishing of silver.

The black substance formed over the silver metal is silver sulphide and its chemical formula is Ag2S.