GC Destroyer Question problem #228 on page 200(2019 Destroyer)

[nsudental]

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I need help in understanding what happens if Lead Iodide has a Ksp of 7 times 10 the power -9 at 25 C. What statement is true if some potassium iodide is added to a saturated solution of PbI2. It says that the solubility product remains the same but the molar solubility decreases......why? Because is it the fact that u are adding Iodine to make the reaction shift to the left and once you are shifting to the left you want to decrease PbI2? What about the other way around?

 

[DAT Destroyer]

Here it is....This is simply the common ion effect......The Iodide shifts the equilibrium to the LEFT,,,,,this will make more of the solid.....hence its solubility will DECREASE.....The Ksp stays the same , since it is only changed by temperature, and not any common ion. If this does not help, kindly consult a standard General Chem text such as Chang or Zumdahl.

Hope this helps

Dr. Jim Romano