Examples of Ksp Calculations in Chemistry

📚 Quick Study Guide

• ⚖️ The solubility product constant, $K_{sp}$, represents the equilibrium constant for the dissolution of a sparingly soluble ionic compound in water.
• 📝 The general form of the dissolution reaction is: $M_xN_y(s) \rightleftharpoons xM^{y+}(aq) + yN^{x-}(aq)$.
• ➗ The $K_{sp}$ expression is: $K_{sp} = [M^{y+}]^x[N^{x-}]^y$, where the brackets denote the molar concentrations at equilibrium.
• 🌡️ Temperature affects $K_{sp}$ values; therefore, $K_{sp}$ is temperature-dependent.
• 🧮 Molar solubility (s) is the number of moles of the solid that dissolve in 1 liter of solution to reach saturation.
• 💡 To calculate $K_{sp}$ from molar solubility, use an ICE table to determine equilibrium concentrations.
• 🧪 To determine if a precipitate will form, calculate the ion product ($Q$) and compare it to $K_{sp}$. If $Q > K_{sp}$, a precipitate will form.

Practice Quiz

1. What is the correct $K_{sp}$ expression for $AgCl(s) \rightleftharpoons Ag^+(aq) + Cl^-(aq)$?
   1. $K_{sp} = [Ag^+][Cl^-]$
   2. $K_{sp} = \frac{[Ag^+][Cl^-]}{[AgCl]}$
   3. $K_{sp} = [AgCl]$
   4. $K_{sp} = \frac{[AgCl]}{[Ag^+][Cl^-]}$
2. The molar solubility of $PbCl_2$ is $1.6 \times 10^{-2}$ M. What is the $K_{sp}$ for $PbCl_2$?
   1. $1.6 \times 10^{-5}$
   2. $3.1 \times 10^{-4}$
   3. $1.6 \times 10^{-4}$
   4. $4.1 \times 10^{-6}$
3. For $BaSO_4$, $K_{sp} = 1.1 \times 10^{-10}$. What is the molar solubility of $BaSO_4$?
   1. $1.1 \times 10^{-10}$ M
   2. $1.05 \times 10^{-5}$ M
   3. $2.2 \times 10^{-5}$ M
   4. $5.5 \times 10^{-11}$ M
4. If the ion product, $Q$, is greater than $K_{sp}$, what will happen?
   1. The solution is unsaturated.
   2. The solution is at equilibrium.
   3. A precipitate will form.
   4. The solid will dissolve completely.
5. What is the effect of the common ion on the solubility of a sparingly soluble salt?
   1. Increases the solubility
   2. Decreases the solubility
   3. Has no effect on the solubility
   4. Causes the solution to become supersaturated
6. The $K_{sp}$ of $AgI$ is $8.5 \times 10^{-17}$. Calculate the solubility of silver iodide in $mol/L$.
   1. $9.2 \times 10^{-9}$
   2. $2.9 \times 10^{-8}$
   3. $4.6 \times 10^{-9}$
   4. $1.8 \times 10^{-8}$
7. Will a precipitate of $Mg(OH)_2$ form if $[Mg^{2+}] = 0.010 M$ and $[OH^-] = 0.0010 M$? ($K_{sp} = 1.8 \times 10^{-11}$ for $Mg(OH)_2$)
   1. Yes
   2. No
   3. Maybe
   4. Cannot be determined