Degree of dissociation
Chemical Equilibrium · Chemistry
Study notes
0.01 M acetic acid, K_a = 1.8×10⁻⁵. Find α and [H⁺]. Step 1: α ≈ √(K_a/C) = √(1.8×10⁻⁵/0.01) = √0.0018 = 0.0424. Step 2: [H⁺] = Cα = 0.01 × 0.0424 = 4.24×10⁻⁴ M. Step 3: pH = −log(4.24×10⁻⁴) = 3.37. Step 4: Check α << 1 ✓ (4.2%), so approximation valid. Only 4% dissociated — weak acid indeed.