Question

The student placed 10 mL of PbCl2 (saturated solution) in the test tube and added a pinch of NaCl. A white precipitate of PbCl2 formed. How will this affect the concentration of Pb2+?

Answer 1

Answer:

Adding NaCl to a saturated PbCl2 solution will decrease the Pb2+ concentration.

Explanation:

If a solution is saturated this means it cannot dissolve more material.  

PbCl2 ⇆ Pb2+ + 2Cl-

Adding more Cl- in the solution is the same thing as trying to dissolve more of the material. In the solution, the concentration of Cl- will increase.

In order for the Ksp to maintain a constant value, the concentration of Pb2+ must decrease if the concentration of Cl- is increased.

Adding NaCl to a saturated PbCl2 solution will decrease the Pb2+ concentration.