When aqueous solutions of (NH_4)_2CO_3 and Mg(NO_3)_2 are mixed, which solid product, if any, is formed?

• A. Mg(NO_3)_2
• B. No solid product is formed
• C. NH_4NO_3
• D. MgCO_3

Answer: (D)

Verified step by step guidance

1. Write the formulas of the reactants and identify the ions present in the solution: (NH_4)_2CO_3 dissociates into 2 NH_4^+ and CO_3^{2-}, and Mg(NO_3)_2 dissociates into Mg^{2+} and 2 NO_3^- ions.
2. Determine the possible combinations of cations and anions that can form new compounds when the solutions are mixed. The possible products are MgCO_3, Mg(NO_3)_2, NH_4NO_3, and (NH_4)_2CO_3.
3. Check the solubility rules to identify which of these possible products are insoluble in water and thus will precipitate as a solid. Carbonates (CO_3^{2-}) of most metals except alkali metals and ammonium are generally insoluble, so MgCO_3 is likely to be insoluble.
4. Confirm that MgCO_3 is the solid product formed by recognizing that Mg^{2+} and CO_3^{2-} ions combine to form an insoluble salt, while the other possible products remain soluble in water.
5. Conclude that the solid precipitate formed when (NH_4)_2CO_3 and Mg(NO_3)_2 solutions are mixed is MgCO_3.