AP Chemistryhardmcq1 pt
Equal volumes of 0.0020 M Pb(NO₃)₂ and 0.0020 M KI are mixed. Does PbI₂ precipitate? (Ksp = 9.8 × 10⁻⁹)
A.No — Q < Ksp
B.Yes — Q > Ksp
C.No — PbI₂ is always soluble
D.Cannot determine
Explanation
Core Concept
Mixing halves each salt: [Pb²⁺] = 0.0010 M and [I⁻] = 0.0010 M. Q = 0.0010 × (0.0010)² = 1.0 × 10⁻⁹, which is below Ksp (9.8 × 10⁻⁹), so the solution stays unsaturated and nothing precipitates.
Correct Answer
ANo — Q < Ksp
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