What precipitate will form when aqueous solutions of sodium carbonate [tex]\(\left( \text{Na}_2\text{CO}_3 \right)\)[/tex] and calcium chloride [tex]\(\left( \text{CaCl}_2 \right)\)[/tex] are mixed?

A. [tex]\(\text{CaCO}_3(s)\)[/tex]

B. [tex]\(\text{Na}_2\text{CO}_3(s)\)[/tex]

C. [tex]\(\text{CaCl}_2(s)\)[/tex]

D. [tex]\(\text{NaCl}(s)\)[/tex]



Answer :

When aqueous solutions of sodium carbonate [tex]\(\text{Na}_2\text{CO}_3\)[/tex] and calcium chloride [tex]\(\text{CaCl}_2\)[/tex] are mixed, a chemical reaction occurs. Let's analyze this reaction step by step.

The reaction can be written as:

[tex]\[ \text{Na}_2\text{CO}_3(aq) + \text{CaCl}_2(aq) \rightarrow \text{CaCO}_3(s) + 2 \text{NaCl}(aq) \][/tex]

Here’s the detailed breakdown of what happens:

1. Reactants: We start with sodium carbonate ([tex]\(\text{Na}_2\text{CO}_3\)[/tex]) and calcium chloride ([tex]\(\text{CaCl}_2\)[/tex]), both in aqueous form. This means that they are dissolved in water and exist as ions.

2. Dissociation in Water: In aqueous solution, sodium carbonate and calcium chloride dissociate into their respective ions:
[tex]\[ \text{Na}_2\text{CO}_3(aq) \rightarrow 2 \text{Na}^+(aq) + \text{CO}_3^{2-}(aq) \][/tex]
[tex]\[ \text{CaCl}_2(aq) \rightarrow \text{Ca}^{2+}(aq) + 2 \text{Cl}^-(aq) \][/tex]

3. Reaction of Ions: When these solutions are mixed, the [tex]\(\text{Ca}^{2+}\)[/tex] ions from [tex]\(\text{CaCl}_2\)[/tex] react with the [tex]\(\text{CO}_3^{2-}\)[/tex] ions from [tex]\(\text{Na}_2\text{CO}_3\)[/tex] to form calcium carbonate ([tex]\(\text{CaCO}_3\)[/tex]).

4. Formation of Precipitate: Calcium carbonate ([tex]\(\text{CaCO}_3\)[/tex]) is insoluble in water and therefore precipitates out of the solution. This is why [tex]\(\text{CaCO}_3\)[/tex] appears as a solid (s):
[tex]\[ \text{Ca}^{2+}(aq) + \text{CO}_3^{2-}(aq) \rightarrow \text{CaCO}_3(s) \][/tex]

5. Remaining Ions in Solution: The sodium ions ([tex]\(\text{Na}^+\)[/tex]) and chloride ions ([tex]\(\text{Cl}^-\)[/tex]) remain in the aqueous solution and do not form a precipitate:
[tex]\[ \text{2 Na}^+(aq) + 2 \text{Cl}^-(aq) \rightarrow 2 \text{NaCl}(aq) \][/tex]

So, the overall balanced chemical equation is:

[tex]\[ \text{Na}_2\text{CO}_3(aq) + \text{CaCl}_2(aq) \rightarrow \text{CaCO}_3(s) + 2 \text{NaCl}(aq) \][/tex]

Thus, the precipitate that forms when aqueous solutions of sodium carbonate ([tex]\(\text{Na}_2\text{CO}_3\)[/tex]) and calcium chloride ([tex]\(\text{CaCl}_2\)[/tex]) are mixed is calcium carbonate ([tex]\(\text{CaCO}_3\)[/tex]).

Therefore, the correct answer is:

[tex]\[ \boxed{\text{CaCO}_3(s)} \][/tex]