It can be either depending on the reaction.
For example. here it is a product.
2Cu + H2O + CO2 + O2 --> Cu(OH)2 + CuCO3
it is a product.
While in this reaction
CuCO3 + 2HCl --> CuCl2 + CO2 + H2O
it is a reactant.
When copper carbonate is added to sodium hydroxide, a chemical reaction occurs to form copper hydroxide and sodium carbonate. Copper hydroxide is a blue solid precipitate, while sodium carbonate remains as a soluble compound in the solution.
Copper(II) carbonate is insoluble in water and doesn't react with sodium sulfate. A green product, visible on ald objects made from copper or copper alloys, is a mixture of copper carbonate and copper hydroxide.
When copper sulfate (blue) and sodium carbonate (colorless) are mixed, a chemical reaction occurs that forms copper carbonate as a product, which is green in color. The green color comes from the copper carbonate that is insoluble in water and precipitates out when the two solutions are mixed.
nothing, a new product can not be formed because their anions are common.
copper(II) carbonate or cupric carbonate
carbon dioxide [CuCO3 --> CuO + CO2]
Copper and carbonate ions form copper carbonate. In practice, copper carbonate usually contains hydroxide ions as well.
The compound you are referring to is copper carbonate, which has the chemical formula CuCO3. It is also known as copper(II) carbonate and is commonly found in nature as the mineral malachite.
Copper Carbonate
When copper carbonate reacts with potassium, it forms copper metal and potassium carbonate. This reaction is a redox reaction where copper is reduced and potassium is oxidized.
Copper carbonate would precipitate if you combined solutions of copper (II) chloride and sodium carbonate.
The precipitate formed when copper sulfate and sodium carbonate are mixed is copper carbonate. This reaction occurs because copper carbonate is insoluble in water and therefore forms a solid precipitate.