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.

AcademicChemistryNCERTClass 10

Copper reacts with moist carbon dioxide in the air to form copper carbonate, and the shiny brown surface of the copper vessel is covered by a green layer of copper carbonate.
  • The citric acid in lemons or tamarind dissolves the coating by neutralising the base copper carbonate.
  • As a result, tarnished copper vessels are washed with lemon or tamarind juice to restore their lustre.

[Extra information:  Reactivity series is the series of arrangement in a vertical column in decreasing order of their reactivities.

The solutions of dilute HCl, dilute HNO3, ZnCl2 and H2O can be kept in a copper container because copper is a noble metal that does not react with HCl or even HNO3.

If we keep the solution in an aluminium container, aluminium reacts with acids to form Zinc chloride.
Water can be stored in either copper or aluminium as they both do not react with copper. ]
Updated on 10-Oct-2022 12:46:59