Three separate 100.0 mL samples of 0.10 M Pb(NO₃)₂ are each mixed with 100.0 mL of one of the following 0.10 M solutions: (1) KI, (2) Na₂CO₃, and (3) a mixture that is 0.10 M in both I⁻ and CO₃²⁻. The solubility-product constants are Ksp(PbI₂)=1.4×10⁻⁸ and Ksp(PbCO₃)=7.4×10⁻¹⁴.
(a) For samples (1) and (2) separately, calculate the ionic product Q for the possible lead(II) precipitate immediately after mixing, before any precipitation occurs. State whether a precipitate forms in each case.
(b) In sample (3), both iodide and carbonate ions are present. Use the given Ksp values and the initial ion concentrations to determine which solid, PbI₂ or PbCO₃, precipitates first. Justify quantitatively.
(c) Write the balanced net ionic equation for formation of the solid that is predicted to precipitate first in sample (3).
(d) Describe qualitatively how continued addition of either I⁻ or CO₃²⁻ could alter which solid is ultimately present at equilibrium.