Evaluate the following reaction: Na2SO4(aq) + BaCl2(aq) → ?. What is the precipitate that forms?

• A. BaSO4(s)
• B. Na2SO4(s)
• C. BaCl2(s)
• D. NaCl(s)

Answer: (A)

Verified step by step guidance

1. Identify the ions present in the reactants. Sodium sulfate (Na2SO4) dissociates into 2 Na\textsuperscript{+} ions and SO4\textsuperscript{2-} ions, while barium chloride (BaCl2) dissociates into Ba\textsuperscript{2+} ions and 2 Cl\textsuperscript{-} ions.
2. Write the possible products by exchanging the ions between the two reactants. The cations and anions swap partners, forming barium sulfate (BaSO4) and sodium chloride (NaCl). The reaction can be written as: \(\mathrm{Na_2SO_4 (aq) + BaCl_2 (aq) \rightarrow BaSO_4 (?) + NaCl (?)}\).
3. Determine the physical states of the products by consulting solubility rules. Barium sulfate (BaSO4) is generally insoluble in water and forms a solid precipitate, while sodium chloride (NaCl) is soluble and remains in aqueous solution.
4. Write the complete balanced chemical equation including physical states: \(\mathrm{Na_2SO_4 (aq) + BaCl_2 (aq) \rightarrow BaSO_4 (s) + 2 NaCl (aq)}\).
5. Conclude that the precipitate formed in this reaction is barium sulfate (BaSO4), which appears as a solid, while sodium chloride remains dissolved in solution.