Question

Which pair of solutions will produce a precipitate when they are mixed?
a. calcium chloride and sodium sulfate
b. magnesium sulfate and zinc(II) nitrate
c. sodium phosphate and lithium chloride
d. lead(II) nitrate and potassium phosphate

Answer 1

a. Na₂SO₄(aq) + CaCl₂(aq) --> CaSO₄(s) + 2NaCl(aq)
Calcium sulfate is insoluble in H₂O.
b. No reaction, so no equation. All the possible salts are soluble.
c. No reaction, so no equation. All the possible salts are soluble.
d. Molecular Equation:
K₃PO₄(aq) + Pb(NO₃)₂(aq) --> KNO₃(aq) + Pb₃(PO₄)₂(s)
Net Ionic Equation:
PO₄^3- + Pb²⁺ → Pb₃(PO₄)₂
Pb₃(PO₄)₂ is insoluble in H₂O.