1. Acid-Base Equilibria Chapter 16

2. Modification to Syllabus DateSectionsTopics Friday 26 Mar17.1 – 17.2Common-ion effect, buffered solutions Monday 29 MarNo classOmit 17.3 – 17.5 Weds 31 Mar---Exam #4

3. Acid-Base Properties of Salt Solutions Acid Solutions: 1) Salts derived from a strong acid and a weak base. NH 4 Cl (s) NH 4 + (aq) + Cl - (aq) H2OH2O NH 4 + (aq) NH 3 (aq) + H + (aq) 2) Salts with small, highly charged metal cations (e.g. Al 3+, Cr 3+, and Be 2+ ) and the conjugate base of a strong acid: Al(H 2 O) 6 (aq) Al(OH)(H 2 O) 5 (aq) + H + (aq) 3+2+

4. Acid Hydrolysis of Al 3+ Hydrolysis ≡ the reaction of an anion or a cation of a salt with water

5. Acid-Base Properties of Salt Solutions Neutral Solutions: Salts derived from a strong acid and a strong base NaCl (s) Na + (aq) + Cl - (aq) H2OH2O Basic Solutions: Salts derived from a strong base and a weak acid. NaCH 3 COOH (s) Na + (aq) + CH 3 COO - (aq) H2OH2O CH 3 COO - (aq) + H 2 O (l) CH 3 COOH (aq) + OH - (aq)

6. CH 3 COOH (aq) + NaOH (aq) CH 3 COONa (aq) + H 2 O (l) CH 3 COO - (aq) + H 2 O (l) OH - (aq) + CH 3 COOH (aq) At equivalence point (pH > 7): Example of when the pH at the equivalence point of a titration will differ from 7:

7. Acid-Base Properties of Salts Solutions in which both the cation and the anion hydrolyze: K b for the anion > K a for the cation, solution will be basic K b for the anion < K a for the cation, solution will be acidic K b for the anion  K a for the cation, solution will be neutral

8. Acid-Base Behavior and Chemical Structure Fig 16.12 Trends in acid-base properties of binary hydrides

9. Factors Affecting Acid Strength

10. Arrhenius acid - a substance that produces H + (H 3 O + ) in water Brønsted acid - a proton donor Lewis acid - a substance that can accept a pair of electrons Lewis base - a substance that can donate a pair of electrons Definition of An Acid H+H+ H O H + OH - acidbase N H H H H+H+ + acidbase N H H H H +

11. Lewis Acids and Bases N H H H acidbase F B F F + F F N H H H Most general theory No protons donated or accepted! Allows treatment of a wider variety of reactions as acid-base reactions Coordinate covalent bond