H2 Chemistry 4 - Theories of Acids and Bases: pH of a Weak Acid

What you will learn

• Sets up the dissociation of 0.10 mol/dm^3 ethanoic acid with Ka = 1.8 x 10^-5 mol/dm^3.
• Builds an ICE table with x as [H+] at equilibrium and applies the small-x assumption (x << 0.10).
• Solves x^2 / 0.10 = Ka to get [H+] = 1.34 x 10^-3 mol/dm^3, well under 5% of 0.10.