When copper(II) ions (Cu²⁺) react with carbonate ions (CO₃²⁻), the expected product is basic copper carbonate (CuCO₃), which is a solid precipitate. This reaction can be represented as follows:
Cu²⁺ + CO₃²⁻ → CuCO₃ (s)
The reaction between Cu²⁺ and CO₃²⁻ should result in the formation of CuCO₃. However, it's important to note that the formation of CuCO₃ may not always be evident as visible gas bubbles of CO₂. The absence of visible gas bubbles does not necessarily indicate the formation of a different compound, such as Cu(OH)₂.
In some cases, the reaction might be slower or the amount of gas produced may be minimal, making it difficult to observe the CO₂ bubbles. Additionally, the solubility of CuCO₃ in water is relatively low, so it may precipitate as a fine solid rather than forming distinct gas bubbles.
If you used bicarbonate ions (HCO₃⁻) instead of carbonate ions (CO₃²⁻), the reaction would proceed differently:
Cu²⁺ + 2HCO₃⁻ → Cu(OH)₂ + 2CO₂ + H₂O
In this case, Cu²⁺ reacts with HCO₃⁻ to form copper(II) hydroxide (Cu(OH)₂), CO₂ gas, and water. The presence of CO₂ gas bubbles confirms the release of gas in this reaction.
Therefore, when using (CO₃)²⁻, the expected product is basic copper carbonate, and the absence of visible CO₂ gas bubbles does not necessarily indicate the formation of Cu(OH)₂.