Lead ions can be precipitated from aqueous solutions by the addition of aqueous iodide: Pb²⁺ (aq) + 2I^- (aq) → PbI₂ (s)
Lead iodide is virtually insoluble in water so that the reaction appears to go to completion. How many milliliters of 3.550 M HI(aq) must be added to a solution containing 0.600 mol of Pb(NO₃) ₂ (aq) to completely precipitate the lead?

Question

Quizplus · Accepted Answer

To completely precipitate 0.600 mol of Pb²⁺, you need 2 moles of I^- for each mole of Pb²⁺. Therefore, you need 1.200 mol of I^-. The concentration of HI is 3.550 M, so the volume required is 1.200 mol / 3.550 M = 0.338 L, which is 338 mL.

Lead Ions Can Be Precipitated from Aqueous Solutions by the Addition