pH, pKa, pKb calculations
Ionic Equilibrium · Chemistry
Study notes
Find the pH of 0.01 M HCl and 0.01 M acetic acid (K_a = 1.8×10⁻⁵). Step 1: HCl (strong): [H⁺] = 0.01 → pH = 2.00. Step 2: Acetic (weak): [H⁺] = √(1.8×10⁻⁵ × 0.01) = 4.24×10⁻⁴. Step 3: pH = −log(4.24×10⁻⁴) = 3.37. Step 4: Same concentration, different pH — strength matters, not just molarity. pK_a of acetic = 4.74; lower pK_a = stronger acid.