Is CaCl2 + (NH4)2CO3 → CaCO3 + 2NH4Cl a precipitation reaction
The Correct Answer and Explanation is:
Correct Answer: Yes, the reaction CaCl₂ + (NH₄)₂CO₃ → CaCO₃ + 2NH₄Cl is a precipitation reaction.
Explanation:
A precipitation reaction occurs when two aqueous solutions react to form an insoluble solid, known as a precipitate. These reactions are a type of double displacement reaction, where the cations and anions of the reactants switch places to form new compounds.
In the given reaction:
Reactants:
- CaCl₂ (calcium chloride) is soluble in water and dissociates into Ca²⁺ and Cl⁻ ions.
- (NH₄)₂CO₃ (ammonium carbonate) is also soluble in water and dissociates into NH₄⁺ and CO₃²⁻ ions.
When these solutions are mixed, calcium ions (Ca²⁺) from calcium chloride combine with carbonate ions (CO₃²⁻) from ammonium carbonate to form calcium carbonate (CaCO₃). Calcium carbonate is insoluble in water, so it forms a white solid precipitate and settles out of the solution.
The other product is ammonium chloride (NH₄Cl), which is soluble in water and remains in the aqueous phase.
So, the reaction:
CaCl₂(aq) + (NH₄)₂CO₃(aq) → CaCO₃(s) + 2NH₄Cl(aq)
fits the definition of a precipitation reaction because it results in the formation of CaCO₃, an insoluble solid.
Net Ionic Equation:
Ca²⁺(aq) + CO₃²⁻(aq) → CaCO₃(s)
This simplified version highlights the formation of the precipitate and removes the spectator ions (NH₄⁺ and Cl⁻), which do not participate in the formation of the solid.
In conclusion, the formation of insoluble calcium carbonate from two soluble ionic compounds makes this a clear example of a precipitation reaction.
