You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Answer

• Green coating on copper is copper carbonate. It is formed by the reaction of copper with carbon dioxide , moisture and oxygen in the atmosphere.
• Copper is a metal . Hence, it forms a basic oxide .
• So, Copper oxide is basic in nature.
• Lemon and tamarind juice are acidic in nature.
• Lemon / tamarind juice reacts with the basic copper oxide to neutralise it, forming salt and water and thus cleaning them.