Question

A student has been collecting silver coins and copper coins. One day she observed a black
coating on silver coins and a green coating on copper coins. Which chemical phenomenon is
responsible for these coatings? Write the names of black and green coatings.

Answer 1

Silver gets tarnished when exposed to the atmosphere which contains pollutant H2S and forms
a black coating of Ag2S.
Copper forms a green deposit on its surface when exposed to moist air. This is usually basic
copper (II) sulphate.