Q: A student dissolves $0.67$ g of $CaSO_4$ in $1$ L of water. The molar mass of $CaSO_4$ is $136.2$ g/mol. What is the molar solubility ($s$) of $CaSO_4$?

$s = \frac{0.67}{136.2} = 4.9 \times 10^{-3}$ mol/L

Q: If the $K_{sp}$ for $AgCl$ is $1.6 \times 10^{-10}$, what is the molar solubility ($s$) of $AgCl$ in pure water?

$s = \sqrt{1.6 \times 10^{-10}} = 1.3 \times 10^{-5}$ mol/L

Q: Calculate the $K_{sp}$ for $CaSO_4$ if its molar solubility is $4.9 \times 10^{-3}$ mol/L.

$K_{sp} = (4.9 \times 10^{-3})^2 = 2.4 \times 10^{-5}$

Q: A solution contains $[Ag^+] = 0.010$ M and $[Cl^-] = 0.010$ M. If $K_{sp}$ for $AgCl$ is $1.6 \times 10^{-10}$, will a precipitate form?

Yes, because $Q = 1.0 \times 10^{-4} > K_{sp}$

Q: For $CaF_2(s) \rightleftharpoons Ca^{2+}(aq) + 2F^-(aq)$, if $K_{sp} = 3.9 \times 10^{-11}$, what is the molar solubility ($s$) of $CaF_2$?

$s = \sqrt[3]{\frac{K_{sp}}{4}} = 2.1 \times 10^{-4}$ mol/L

Q: A solution is prepared by mixing $AgNO_3$ and $NaCl$ so that $[Ag^+] = 1.0 \times 10^{-5}$ M and $[Cl^-] = 2.0 \times 10^{-5}$ M. If $K_{sp}$ for $AgCl$ is $1.6 \times 10^{-10}$, what is $Q$ and will a precipitate form?

$Q = 2.0 \times 10^{-10}$; Yes, a precipitate will form.

Question 1

Which of the following best describes the solubility product constant ($K_{sp}$) for a slightly soluble salt?

Accepted Answer

It is the equilibrium constant for the dissolution of a slightly soluble salt into its ions.

Question 2

Given the dissolution of $AgCl(s) \rightleftharpoons Ag^+(aq) + Cl^-(aq)$, which is the correct $K_{sp}$ expression?

Accepted Answer

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

Question 3

A student dissolves $0.67$ g of $CaSO_4$ in $1$ L of water. The molar mass of $CaSO_4$ is $136.2$ g/mol. What is the molar solubility ($s$) of $CaSO_4$?

Accepted Answer

$s = \frac{0.67}{136.2} = 4.9 	imes 10^{-3}$ mol/L

Question 4

For the dissolution $Ag_2CrO_4(s) \rightleftharpoons 2Ag^+(aq) + CrO_4^{2-}(aq)$, what is the correct $K_{sp}$ expression?

Accepted Answer

$K_{sp} = [Ag^+]^2[CrO_4^{2-}]$

Question 5

If the $K_{sp}$ for $AgCl$ is $1.6 	imes 10^{-10}$, what is the molar solubility ($s$) of $AgCl$ in pure water?

Accepted Answer

$s = \sqrt{1.6 	imes 10^{-10}} = 1.3 	imes 10^{-5}$ mol/L

Question 6

Calculate the $K_{sp}$ for $CaSO_4$ if its molar solubility is $4.9 	imes 10^{-3}$ mol/L.

Accepted Answer

$K_{sp} = (4.9 	imes 10^{-3})^2 = 2.4 	imes 10^{-5}$

Question 7

A solution contains $[Ag^+] = 0.010$ M and $[Cl^-] = 0.010$ M. If $K_{sp}$ for $AgCl$ is $1.6 	imes 10^{-10}$, will a precipitate form?

Accepted Answer

Yes, because $Q = 1.0 	imes 10^{-4} > K_{sp}$

Question 8

Which of the following statements is TRUE regarding the relationship between $Q$ and $K_{sp}$ for precipitation?

Accepted Answer

A precipitate forms when $Q > K_{sp}$.

Question 9

For $CaF_2(s) ightleftharpoons Ca^{2+}(aq) + 2F^-(aq)$, if $K_{sp} = 3.9 	imes 10^{-11}$, what is the molar solubility ($s$) of $CaF_2$?

Accepted Answer

$s = \sqrt[3]{\frac{K_{sp}}{4}} = 2.1 	imes 10^{-4}$ mol/L

Question 10

Which of the following is the correct $K_{sp}$ expression for $Ca_3(PO_4)_2(s) \rightleftharpoons 3Ca^{2+}(aq) + 2PO_4^{3-}(aq)$?

Accepted Answer

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

Question 11

A solution is prepared by mixing $AgNO_3$ and $NaCl$ so that $[Ag^+] = 1.0 	imes 10^{-5}$ M and $[Cl^-] = 2.0 	imes 10^{-5}$ M. If $K_{sp}$ for $AgCl$ is $1.6 	imes 10^{-10}$, what is $Q$ and will a precipitate form?

Accepted Answer

$Q = 2.0 	imes 10^{-10}$; Yes, a precipitate will form.

Question 12

Which of the following best defines molar solubility?

Accepted Answer

The number of moles of solute dissolved in 1 L of a saturated solution.

Question 13

If the $K_{sp}$ for $Ag_2CrO_4$ is $9.3 	imes 10^{-12}$ and its molar solubility is $1.3 	imes 10^{-4}$ mol/L, what is the equilibrium concentration of $Ag^+$ ions?

Accepted Answer

$[Ag^+] = 2 	imes 1.3 	imes 10^{-4} = 2.6 	imes 10^{-4}$ mol/L

Question 14

A solution is unsaturated with respect to $AgCl$ if:

Accepted Answer

$Q < K_{sp}$

Question 15

Which of the following would increase the likelihood of precipitation in a solution containing $Ca^{2+}$ and $F^-$ ions?

Accepted Answer

Increasing the concentration of either $Ca^{2+}$ or $F^-$ ions so that $Q > K_{sp}$.

Question 16

If the $K_{sp}$ for $CaF_2$ is $3.9 	imes 10^{-11}$, what is the equilibrium concentration of $F^-$ ions in a saturated solution?

Accepted Answer

$[F^-] = 2s = 2 	imes 2.1 	imes 10^{-4} = 4.2 	imes 10^{-4}$ mol/L

Question 17

Which of the following is NOT a correct use of the solubility product constant ($K_{sp}$)?

Accepted Answer

Comparing the solubility of salts with different stoichiometry directly using $K_{sp}$ values.

Question 18

A patient receives an intravenous solution containing $Ca^{2+}$ and $SO_4^{2-}$ ions. If the product $[Ca^{2+}][SO_4^{2-}]$ exceeds the $K_{sp}$ for $CaSO_4$, what medical concern might arise?

Accepted Answer

Precipitation of $CaSO_4$ in the bloodstream, potentially causing blockages.

Solubility Equilibria and the Solubility Product Constant (Ksp)

Study Guide - Practice Questions

Study Guide - Flashcards