AP Chemistry Questions on Calculating pH of Strong Acids and Bases

🧪 Quick Study Guide

⚛️
• Strong acids and bases completely dissociate in water.
➕
• pH is a measure of the concentration of hydrogen ions ($H^+$) in a solution.
➖
• pOH is a measure of the concentration of hydroxide ions ($OH^−$) in a solution.
🔢
• The formula for calculating pH is: $pH = -log[H^+]$.
💧
• The formula for calculating pOH is: $pOH = -log[OH^-]$.
⚖️
• At $25^\circ C$, $pH + pOH = 14$.
💡
• For strong acids, $[H^+]$ is equal to the concentration of the acid.
🧪
• For strong bases, $[OH^-]$ is equal to the concentration of the base, considering the number of hydroxide ions per mole of base (e.g., for $Ba(OH)_2$, $[OH^-] = 2 \times [Ba(OH)_2]$).

🧪 Practice Quiz

1. What is the pH of a 0.01 M solution of HCl?
1. 2
2. 12
3. -2
4. 0.01
2. What is the pOH of a 0.001 M solution of NaOH?
1. 3
2. 11
3. -3
4. 0.001
3. What is the pH of a 0.005 M solution of $H_2SO_4$? (Assume complete dissociation)
1. 2
2. 2.3
3. 1.7
4. -2.3
4. What is the pH of a $1.0 \times 10^{-4}$ M solution of KOH?
1. 4
2. 10
3. -4
4. 0.0001
5. A solution has a pH of 3. What is the concentration of $H^+$ ions in the solution?
1. $1 \times 10^{-3}$ M
2. $1 \times 10^{3}$ M
3. 3 M
4. -3 M
6. What is the pH of a 0.002 M solution of $Ba(OH)_2$? (Assume complete dissociation)
1. 2.4
2. 2.7
3. 11.6
4. 11.3
7. A solution has a pOH of 5. What is its pH at $25^\circ C$?
1. 5
2. 9
3. -5
4. 19