Which of the following equations best represents the behavior of BaSO_4 in water?

• A. BaSO_4 (s) ightarrow BaSO_4 (aq)
• B. BaSO_4 (aq) ightarrow Ba^{2+} (aq) + SO_4^{2-} (aq)
• C. BaSO_4 (s) ightarrow Ba^{2+} (s) + SO_4^{2-} (s)
• D. BaSO_4 (s) ightarrow Ba^{2+} (aq) + SO_4^{2-} (aq)

Answer: (D)

Verified step by step guidance

1. Recognize that barium sulfate (BaSO_4) is a sparingly soluble salt, meaning it does not dissolve significantly in water but does dissociate slightly into its ions.
2. Understand that when a solid ionic compound dissolves in water, it dissociates into its constituent ions in aqueous form, not as solids or as the undissolved compound in solution.
3. Write the dissolution and dissociation process of BaSO_4 in water as an equilibrium reaction where solid BaSO_4 separates into barium ions (Ba^{2+}) and sulfate ions (SO_4^{2-}), both in aqueous form.
4. Express this process with the correct chemical equation: \(\text{BaSO}_4 (s) \rightarrow \text{Ba}^{2+} (aq) + \text{SO}_4^{2-} (aq)\), indicating the solid salt dissociates into aqueous ions.
5. Note that the other options are incorrect because BaSO_4 does not simply dissolve as the intact compound in aqueous form, nor does it dissociate into solid ions.