Question

Copper and brass vessels are cleaned with lemon

Answer 1

1) Copper undergoes oxidation in air to form black copper oxides. Copper oxide react slowly with carbon dioxide in air and gains a green coat. Thus green substance is Copper carbonate.

2) Lemon contain acids. So lemon is used to clean the copper and brass vessels.

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Answer 2

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Ans: The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.