When aqueous solutions of Pb(NO3)2 and K2SO4 are mixed, which formula represents the precipitate that forms?

• A. K2SO4
• B. KNO3
• C. Pb(NO3)2
• D. PbSO4

Answer: (D)

Verified step by step guidance

1. Identify the ions present in the solutions before mixing: Pb(NO3)2 dissociates into Pb^{2+} and NO_3^{-} ions, and K_2SO_4 dissociates into K^{+} and SO_4^{2-} ions.
2. Determine the possible combinations of cations and anions after mixing: Pb^{2+} can combine with SO_4^{2-} to form PbSO_4, K^{+} can combine with NO_3^{-} to form KNO_3, and other combinations are the original ions in solution.
3. Recall the solubility rules: most sulfate salts are soluble except those of Pb^{2+}, Ba^{2+}, and Ca^{2+}, which tend to form precipitates. Potassium salts and nitrates are generally soluble.
4. Based on solubility, predict which compound will precipitate: PbSO_4 is insoluble and will form a solid precipitate, while KNO_3 and the original salts remain dissolved.
5. Write the formula of the precipitate as PbSO_4, representing lead(II) sulfate, the solid formed when Pb^{2+} and SO_4^{2-} ions combine in solution.