a lady has been collecting silver and gold coins . one day she observed a black coating on silver coins and green coating on copper coins .which chemical phenomenon is responsible for these coating ? write chemical names of black and green coating.
The phenomena responsible for the formation of a coating on copper and silver objects is known as corrosion. Silver turns black due to the formation of silver sulphide (Ag2S) while copper turns green due to the formation of a mixture of copper carbonate and copper hydroxide [(CuCO3). Cu(OH)2].