Question

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 1

Copper reacts with moist carbon dioxide in the air and slowly tosses its shiny brown surface and gains a green coat. This green substance is basic copper carbonate. Citric acid and tartaric acid neutralise copper carbonate. Hence citric or tartaric acid are effective in cleaning the vessel.