Describe the chemical reaction between citric acid and copper carbonate

When Citric acid (H₃C₆H₅O₇) reacts with Copper(II) carbonate (CuCO₃) or more commonly with basic copper carbonate (Cu₂(OH)₂CO₃) on a copper surface, acid-carbonate reaction occurs: the acid supplies H⁺ which reacts with CO₃²⁻ to release CO₂ gas and H₂O, while copper ions enter solution and form a copper-citrate complex/salt. For example:

CuCO3(s)+2H₃C₆H₅O₇(aq)→Cu(C₆H₅O₇)₂(aq)+CO₂(g)+2H₂O(l)

This fits the generic acid + carbonate → salt + CO₂ + H₂O model. In practice, the copper citrate complex (e.g., Copper(II) citrate) is formed. Thus cleaning of tarnished copper with a citric‐acid solution works by dissolving the carbonate patina via acid reaction and forming soluble copper citrate.