Q: If the molar solubility ($$s) of $$AgBr in water is $$6.9 \times 10$$^{-7}$$ mol L$$^{-1}$$, what is the K$$_{sp}$$ for AgBr?

$$K_{sp} = (6.9 \times 10$$^{-7}$$)^2 = 4.8$$ \times $$10^{-13}$

Q: If the $$K_{sp} of $$PbI$$_2 is$$ $$7.9 \times 10$$^{-9}$$ and the concentration of I$$^-$$ is 0.10$ M, what is the molar solubility (s$) of PbI_2$?

$$s = \dfrac{K_{sp}}{[I^-]^2} = \dfrac{7.9 \times 10$$^{-9}$$}{(0.10)^2$} = 7.9 \times 10$$^{-7}$$

Question 1

Which of the following best describes the solubility product ($$K_{sp}) $$for a salt such as AgCl?

Accepted Answer

It is the product of the concentrations of Ag$$^+$$ and Cl$$^-$$ ions at equilibrium, excluding the solid AgCl.

Question 2

Given the dissolution of CaF$$_2 in $$water: $$\mathrm{$$CaF_2$$(s) \rightleftharpoons Ca$$^{2+}$$(aq) + 2F$$^{-}$$(aq)}$$, which is the correct expression for its solubility product ($$K_{sp}$$)?

Accepted Answer

$$K_{sp} = [\mathrm{Ca$$^{2+}$$}][\mathrm{F$$^{-}$$}]^2$$

Question 3

A salt has a $$K_{sp}$$ value of $$1.8 	imes 10$$^{-10}$$ at 25$$^\circ$$C. Which statement is true about its solubility?

Accepted Answer

It is slightly soluble in water.

Question 4

Which of the following salts is expected to be insoluble in water according to general solubility rules?

Accepted Answer

PbCl$$_2$$

Question 5

If the molar solubility ($$s) of $$AgBr in water is $$6.9 	imes 10$$^{-7}$$ mol L$$^{-1}$$, what is the K$$_{sp}$$ for AgBr?

Accepted Answer

$$K_{sp} = (6.9 	imes 10$$^{-7}$$)^2 = 4.8$$ 	imes $$10^{-13}$

Question 6

Which of the following best explains why the solubility of PbCl$$_2$$ decreases when Pb(NO$$_3$$)$$_2 is $$added to its saturated solution?

Accepted Answer

The addition of Pb(NO$$_3$$)$$_2$$ increases the concentration of Pb$$^{2+}$$, causing Q$$_{sp} to $$exceed K$$_{sp}$$ and shifting the equilibrium to the left, precipitating PbCl$$_2.$$

Question 7

Which salt would be expected to form a precipitate when mixed with AgNO$$_3 in $$solution?

Accepted Answer

NaCl

Question 8

A student dissolves CaF$$_2 in $$water. If the molar solubility is $$s$$, what are the equilibrium concentrations of Ca$$^{2+}$$ and F$$^-$$?

Accepted Answer

Ca$$^{2+}$$: $$s$$, F$$^-$$: $$2s$$

Question 9

Which of the following statements about the solubility product ($$K_{sp}) is $$correct?

Accepted Answer

$$K_{sp} is $$only comparable for salts with the same molar ratios of ions.

Question 10

What is the effect of adding NaI to a saturated solution of PbI$$_2$$?

Accepted Answer

The solubility of PbI$$_2$$ decreases due to the common ion effect.

Question 11

A solution contains 0.10 M NaI. What is the approximate equilibrium concentration of I$$^-$$ after PbI$$_2 is $$added, assuming its solubility is very small?

Accepted Answer

$$0.10 + 2s$$

Question 12

Which salt is borderline soluble according to the general solubility rules?

Accepted Answer

Ca(OH)$$_2$$

Question 13

If the $$K_{sp} of $$PbI$$_2 is$$ $$7.9 	imes 10$$^{-9}$$ and the concentration of I$$^-$$ is 0.10$ M, what is the molar solubility (s$) of PbI_2$?

Accepted Answer

$$s = \dfrac{K_{sp}}{[I^-]^2} = \dfrac{7.9 	imes 10$$^{-9}$$}{(0.10)^2$} = 7.9 	imes 10$$^{-7}$$

Question 14

Which of the following salts is soluble in water according to the general solubility rules?

Accepted Answer

Na$$_2S$$

Question 15

A student mixes solutions of AgNO$$_3$$ and NaCl. What is the expected outcome?

Accepted Answer

A precipitate of AgCl forms.

Question 16

Which of the following best describes the common ion effect?

Accepted Answer

The solubility of a salt decreases in the presence of a common ion.

Question 17

Which salt is insoluble in water except when paired with Na$$^+$$, K$$^+$$, or NH$$_4^+$$?

Accepted Answer

PO$$_4$$^{3-}$$ salts

Question 18

A solution contains Sr(OH)$$_2. $$According to solubility rules, how would you classify its solubility?

Accepted Answer

Borderline soluble

Question 19

Which of the following is a correct statement about the calculation of $$K_{sp}$$?

Accepted Answer

$$K_{sp} is $$calculated using the concentrations of ions in a saturated solution, excluding solids.

Question 20

Which salt is insoluble in water except when paired with Na$$^+$$, K$$^+$$, NH$$_4^+$$, Ca$$^{2+}$$, Sr$$^{2+}$$, or Ba$$^{2+}$$?

Accepted Answer

S$$^{2-}$$ salts

Solubility Product, Solubility Rules, and the Common Ion Effect

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