Q: If the solubility of $$\mathrm{$$PbCl_2$$} in $$water at $$25^\circ\mathrm{C} is$$ $$2.4 \times 10$$^{-3}$$\ \mathrm{mol/L}$$, what is its $$K_{sp}$$ value?

$$K_{sp} = 5.5 \times 10$$^{-5}$$

Question 1

Which of the following best describes a saturated solution?

Accepted Answer

A solution in which the maximum amount of solute has been dissolved and any additional solute will not dissolve.

Question 2

Given the equilibrium $$\mathrm{$$BaSO_4$$(s) \rightleftharpoons Ba$$^{2+}$$(aq) + SO_4$^{2-}(aq)}$$, what is the correct expression for the solubility product $$K_{sp}$$?

Accepted Answer

$$K_{sp} = [Ba$$^{2+}$$] [SO_4$^{2-}]$$

Question 3

Which of the following will increase the solubility of a salt containing a basic anion, such as $$\mathrm{Mg(OH)_2}$$?

Accepted Answer

Decreasing the pH of the solution (making it more acidic).

Question 4

A solution contains $$[Pb$$^{2+}$$] = 0.015\ \mathrm{M}$$ and $$[I^-] = 0.023\ \mathrm{M}. $$Will $$\mathrm{$$PbI_2$$}$$ precipitate if $$K_{sp} = 6.6 	imes 10$$^{-9}$$?

Accepted Answer

Yes, because $$Q \u003e K_{sp}.$$

Question 5

Which statement about the common-ion effect is correct?

Accepted Answer

Adding a common ion decreases the solubility of a salt.

Question 6

What is the $$K_{sp}$$ expression for $$\mathrm{Ca_3$(PO_4$)_2}$$?

Accepted Answer

$$K_{sp} = [Ca$$^{2+}$$]^3 [PO_4$^{3-}]^2$$

Question 7

If the solubility of $$\mathrm{$$PbCl_2$$} in $$water at $$25^\circ\mathrm{C} is$$ $$2.4 	imes 10$$^{-3}$$\ \mathrm{mol/L}$$, what is its $$K_{sp}$$ value?

Accepted Answer

$$K_{sp} = 5.5 	imes 10$$^{-5}$$

Question 8

Which of the following is true regarding the relationship between $$K_{sp}$$ and solubility?

Accepted Answer

$$K_{sp} is $$related to solubility, but comparing $$K_{sp}$$ values is only valid for salts with the same cation:anion ratio.

Question 9

A student adds $$\mathrm{NaF} to a $$solution containing $$\mathrm{$$CaF_2$$}. $$What will happen to the solubility of $$\mathrm{$$CaF_2$$}$$?

Accepted Answer

The solubility of $$\mathrm{$$CaF_2$$}$$ will decrease due to the common-ion effect.

Question 10

Which of the following best explains why $$\mathrm{Mg(OH)_2} is $$more soluble in acidic solution than in basic solution?

Accepted Answer

Acidic solution decreases the concentration of $$\mathrm{OH^-}$$ ions, shifting equilibrium to dissolve more $$\mathrm{Mg(OH)_2}.$$

Question 11

If $$Q \u003c K_{sp}$$ for a salt in solution, what will happen?

Accepted Answer

More solid will dissolve until $$Q = K_{sp}.$$

Question 12

Which of the following is NOT a correct way to express solubility?

Accepted Answer

Volume of solute per mass of solvent (L/g)

Question 13

A solution is carefully cooled and contains more solute than can normally dissolve. What type of solution is this?

Accepted Answer

Supersaturated solution

Question 14

Which of the following salts will have its solubility increased in a basic solution?

Accepted Answer

A salt with an acidic cation

Question 15

If the $$K_{sp} of$$ $$\mathrm{Cu_3$(PO_4$)_2} at$$ $$25^\circ\mathrm{C} is$$ $$7.6 	imes 10$$^{-37}$$, what is the molar solubility of this salt at 25$$^\circ\mathrm{C}$$?

Accepted Answer

$$s = 2.1 	imes 10$$^{-9}$$\ \mathrm{mol/L}$$

Question 16

Which of the following is true about the effect of temperature on the solubility of most solid salts?

Accepted Answer

Increasing temperature generally increases the solubility of solids.

Question 17

What is the correct $$K_{sp}$$ expression for $$\mathrm{$$PbCl_2$$}$$?

Accepted Answer

$$K_{sp} = [Pb$$^{2+}$$] [Cl^-]^2$$

Question 18

A solution contains $$[Ni$$^{2+}$$] = 0.65\ \mathrm{M}$$ and $$[OH^-] = 0.0053\ \mathrm{M}. $$Will $$\mathrm{Ni(OH)_2}$$ precipitate if $$K_{sp} = 2.0 	imes 10$$^{-15}$$?

Accepted Answer

Yes, because $$Q \u003e K_{sp}.$$

Solubility Equilibria: Concepts, Calculations, and Applications

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