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CHAPTER 17
Concept Explorations
17.15. Solubility and Solubility Product
You put 0.10-mol samples of KNO3 , (NH4 )2 S, K2 S, MnS, AgCl, and BaSO4 into separate flasks and
add 1.0 L of water to each one. Then you stir the solutions for 5 minutes at room temperature. Assume
that you have 1.0 L of solution in each case.
a.
Are there any beakers where you would observe solid still present? How do you know?
b.
Can you calculate the potassium ion concentration, K+, for the solutions of KNO3 and K2 S?
If so, do the calculations, and then compare these K+ concentrations.
c.
For the solutions of (NH4 )2 S, K2S, and MnS, how do the concentrations of sulfide ion, S2–,
compare? (You don’t need to calculate an answer at this point; just provide a rough
comparison.) Be sure to justify your answer.
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Chapter 17: Concept Explorations
d.
Are there any cases where you need more information to calculate the sulfide-ion
concentration for the solutions of (NH4 )2 S, K2 S, and MnS from part c? If so, what additional
information do you need?
e.
Consider all of the solutions listed at the beginning of this problem. For which ones do you
need more information than is given in the question to determine the concentrations of the
ions present? Where can you find this information?
f.
How is the solubility of an ionic compound related to the concentrations of the ions of the
dissolved compound in solution?
17.16. Solubility Equilibria
Consider three hypothetical ionic solids: AX, AX2 , and AX3 (each X forms X−). Each of these solids has
the same Ksp value, 5.5 × 10−7. You place 0.25 mol of each compound in a separate container and add
enough water to bring the volume to 1.0 L in each case.
a.
Write the chemical equation for each of the solids dissolving in water.
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Chapter 17: Concept Explorations
b.
Would you expect the concentration of each solution to be 0.25 M in the compound?
Explain, in some detail, why or why not.
c.
Would you expect the concentrations of the A cations (A+, A2+, and A3+) in the three solutions
to be the same? Does just knowing the stoichiometry of each reaction help you determine the
answer, or do you need something else? Explain your answer in detail, but without doing any
arithmetic calculations.
d.
Of the three solids, which one would you expect to have the greatest molar solubility?
Explain in detail, but without doing any arithmetic calculations.
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Chapter 17: Concept Explorations
e.
Calculate the molar solubility of each compound.