AP Chemistry Exam Questions on Strong Acid/Base Equilibrium

🧪 Quick Study Guide

• 💪 Strong acids and bases completely dissociate in water. This means that the concentration of $H^+$ (for acids) or $OH^-$ (for bases) is equal to the initial concentration of the acid or base.
• ➗ For strong acids, $[H^+] = [Acid]$. For strong bases, $[OH^-] = [Base]$. This simplifies pH and pOH calculations.
• 💧 Remember the autoionization of water: $K_w = [H^+][OH^-] = 1.0 \times 10^{-14}$ at 25°C. This is crucial for relating $[H^+]$ and $[OH^-]$.
• 📏 pH is calculated as $pH = -log[H^+]$, and pOH is calculated as $pOH = -log[OH^-]$.
• 🌡️ Also, $pH + pOH = 14$ at 25°C. This relationship allows you to easily convert between pH and pOH values.
• 📝 For strong acid/strong base titrations, the equivalence point occurs when moles of acid = moles of base.
• 💡 The pH at the equivalence point in a strong acid/strong base titration is 7.0.

Practice Quiz

1. What is the pH of a 0.010 M solution of HCl (a strong acid)?
   1. 2.0
   2. 12.0
   3. 0.010
   4. -2.0
2. What is the pOH of a 0.0050 M solution of NaOH (a strong base)?
   1. 2.30
   2. 11.70
   3. 0.0050
   4. -2.30
3. What is the $[H^+]$ concentration in a solution with a pH of 4.0?
   1. $1.0 \times 10^{-4}$ M
   2. $1.0 \times 10^{4}$ M
   3. 4.0 M
   4. -4.0 M
4. What is the $[OH^-]$ concentration in a solution with a pOH of 9.0?
   1. $1.0 \times 10^{-9}$ M
   2. $1.0 \times 10^{9}$ M
   3. 9.0 M
   4. -9.0 M
5. A 0.10 M solution of which of the following would have the highest pH?
   1. HCl
   2. HBr
   3. HI
   4. NaOH
6. What is the pH of a solution formed by adding 0.01 moles of HCl to enough water to make 1.0 L of solution?
   1. 1
   2. 2
   3. 12
   4. 13
7. What is the pOH of a solution with a pH of 3.5?
   1. 3.5
   2. 10.5
   3. -3.5
   4. -10.5