Schedule Today (2/22): Continue Chapter 7 Should have read Sections 7.7-7.9 (at least) Monday (2/25): Finish Chapter 7 Start Chapter 8 on Wednesday Wednesday (2/27): Start Chapter 8 Should have read Sections 8.1-8.5 (at least) Friday (2/29): Continue Chapter 8 Should have read through Section 8.7 (at least)

Clicker Question You add 1.00 x 10–7 mol of HCl to 1.0 L of water at 25°C. What is the pH of the solution? a) 6.70 b) 6.79 c) 7.00 d) 7.21 e) 7.30

Problem Solving: A Journey Where Are We Going?: What are we trying to solve? What does this mean? Where Have We Been?: What do we know? What is given in the problem, and what is our knowledge base? How Do We Get There?: How do we connect what we know to what we are trying to solve? Diagrams and more questions can be useful.

Problem Solving: Acids-Bases What are the major species? HF in water: HF and H2O HCl in water: H3O+, Cl–, and H2O What are the reactions in solution? Always: H2O + H2O H3O+(aq) + OH–(aq) Weak acid: HA(aq) + H2O H3O+(aq) + A–(aq) Which reaction dominates? Look at K values for the reactions

Clicker Question a) 3.18 b) 5.16 c) 6.37 d) 8.34 e) 10.32 Determine the pH of a 1.00M aqueous solution of H2CO3 at 25°C. Ka1 = 4.3 x 10-7 Ka2 = 4.8 x 10-11 a) 3.18 b) 5.16 c) 6.37 d) 8.34 e) 10.32

Polyprotic Acids Ka1 = 4.3 x 10-7 pKa1 = 6.37 Ka2 = 4.8 x 10-11 pKa2 = 10.32

Polyprotic Acids Ka1 = 4.3 x 10-7; pKa1 = 6.37 Ka2 = 4.8 x 10-11; pKa2 = 10.32 Ka1 = 7.5 x 10-3; pKa1 = 2.12 Ka2 = 6.2 x 10-8; pKa2 = 7.21 Ka3 = 4.8 x 10-13; pKa3 = 12.32

Polyprotic Acids For a solution of a polyprotic acid (X M of H2A or H3A) we generally only concern ourselves with the first dissociation. Why? See Examples 7.10 and 7.11 in your text for H2SO4, and how concentration plays a role in this.

Clicker Question a) 2.90 b) 5.10 c) 7.00 d) 8.90 e) 11.10 Determine the pH of a 0.10M aqueous solution of KCN at 25°C. (for HCN Ka = 6.2 x 10–10) a) 2.90 b) 5.10 c) 7.00 d) 8.90 e) 11.10