Question

What reaction takes place when copper gets tarnished. Name the products formed while it gets cleaned when we rub it with lemon or tamarind juice.

Answer 1

When copper gets tarnished , it first gets black colour on it i.e. the copper vessel gets oxidised. Then the blackened copper vessel reacts with CO2 present in air to form CuCO3 . Thus the copper vessel thus develops green spots on it.

Tarnished copper vessels are cleaned with lemon or tamarind juice , as they are acids and they neutralise the CuCO3 ( which is a base) giving out salt and water . This salt is easily washed by water leaving the copper vessel shiny . Thus , cleaning with lemon or tamarind will shine the vessel.

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