In this reaction, [tex]$BaCO_3$[/tex] is the:

[tex]\[BaCl_2(aq) + Na_2CO_3(aq) \rightarrow BaCO_3(s) + 2NaCl(aq)\][/tex]

A. excess reagent.
B. reactant.
C. dissociated compound.
D. precipitate.



Answer :

To answer the question, let's analyze the given chemical reaction step-by-step.

The reaction provided is:

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

We need to determine the role of [tex]\(\text{BaCO}_3\)[/tex] in this reaction.

1. Reactants and Products Identification:
- The reactants are substances that start off the reaction. Here, [tex]\(\text{BaCl}_2(aq)\)[/tex] and [tex]\(\text{Na}_2\text{CO}_3(aq)\)[/tex] are the reactants.
- The products are substances formed as a result of the reaction. Here, [tex]\(\text{BaCO}_3(s)\)[/tex] and [tex]\(\text{NaCl}(aq)\)[/tex] are the products.

2. Excess Reagent:
- The excess reagent is the reactant that is not completely consumed in the reaction, hence there is some leftover after the reaction is complete. In this case, we are not provided information about the quantities of the reactants so we have no basis to identify an excess reagent.

3. Precipitate Formation:
- A precipitate is a solid product that forms from a solution during a chemical reaction. Here, [tex]\(\text{BaCO}_3(s)\)[/tex] is in the solid state, as indicated by the symbol [tex]\((s)\)[/tex], suggesting it is a precipitate.

4. Dissociated Compound:
- Since we know [tex]\(\text{BaCO}_3\)[/tex] is a product and forms as a solid precipitate, it does not remain dissociated in the solution.

Given these considerations, [tex]\(\text{BaCO}_3\)[/tex] is identified as the precipitate in the given reaction.

Thus, the answer to the question is:
[tex]\[ \text{precipitate} \][/tex]