1. Topic 1.5 Titrations

2. Titrations In a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete. Equivalence point – the point at which the reaction is complete Indicator – substance that changes color at the endpoint (hopefully close to the equivalence point) Slowly add base to unknown acid UNTIL The indicator changes color (pink) 4.7

3. Strong Acid-Strong Base Titrations NaOH (aq) + HCl (aq) H 2 O (l) + NaCl (aq) OH - (aq) + H + (aq) H 2 O (l) 16.4 100% ionization! No equilibrium

4. The titration equation can be used for neutralization reactions (strong acid-strong base). NaOH (aq) + HCl (aq) → H 2 O (l) + NaCl (aq) Bb x Ca x Va = Ba x Cb x Vb Titration equation Balanced base coefficeint Balanced acid coefficeint Concentratio n of acid Volume of acid Concentration of base Volume of base

5. A titration of a 25.00 mL sample of a hydrochloric acid solution of unknown molarity reaches the equivalence point when 38.28 mL of 0.4370 M NaOH solution has been added. What is the molarity of the HCl solution? NaOH (aq) + HCl (aq) → NaCl (aq) +H 2 O (l) 0.6691 M HCl

6. A 50.00 mL sample of a sodium hydroxide solution is titrated with a 1.605 M solution of sulfuric acid. The titration requires 24.09 mL of the acid solution to reach the equivalence point. What is the molarity of the base solution? H 2 SO 4(aq) + 2NaOH (aq) → Na 2 SO 4(aq) + 2H 2 O (l) 1.547 M NaOH