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

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Solution

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].

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

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].