1. 1 Chapter 8 Acids and Bases 8.3 Strengths of Acids and Bases

2. 2 A strong acid completely ionizes (100%) in aqueous solutions. HCl(g) + H 2 O(l) H 3 O + (aq) + Cl − (aq) A weak acid dissociates only slightly in water to form a few ions in aqueous solutions. H 2 CO 3 (aq) + H 2 O(l) H 3 O + (aq) + HCO 3 − (aq) Strengths of Acids

3. 3 Strong Acids In water, the dissolved molecules of a strong acid dissociate into ions. give large concentrations of H 3 O + and the anion (A - ). Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

4. 4 Weak Acids In weak acids, only a few molecules dissociate. most of the weak acid remains as the undissociated (molecular) form of the acid. the concentrations of the H 3 O + and the anion (A - ) are small. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings HA(aq) + H 2 O(l) H 3 O(aq) + A − (aq)

5. 5 Strong and Weak Acids In an HCl solution, the strong acid HCl dissociates 100%. A solution of the weak acid CH 3 COOH contains mostly molecules and a few ions.

6. 6 Strong acids make up six of all the acids. have weak conjugate bases. Strong Acids

7. 7 Weak Acids Weak acids make up most of the acids. have strong conjugate bases.

8. 8 Comparing Strong and Weak Acids

9. 9 Strong Bases Strong bases are formed from metals of Groups 1A (1) and 2A (2). include LiOH, NaOH, KOH, and Ca(OH) 2. dissociate completely in water. KOH(s) K + (aq) + OH − (aq)

10. 10 Weak Bases Weak bases are most other bases. dissociate only slightly in water. form only a few ions in water. NH 3 (g) + H 2 O(l) NH 4 + (aq) + OH − (aq)

11. 11 Learning Check Identify each of the following as a strong or weak acid or base. A. HBr B. HNO 2 C. NaOH D. H 2 SO 4 E. Cu(OH) 2

12. 12 Solution Identify each of the following as a strong or weak acid or base. A. HBrstrong acid B. HNO 2 weak acid C. NaOHstrong base D. H 2 SO 4 strong acid E. Cu(OH) 2 weak base

13. 13 Learning Check Identify the stronger acid in each pair. 1. HNO 2 or H 2 S 2. HCO 3 − or HBr 3. H 3 PO 4 or H 3 O +

14. 14 Solution Identify the stronger acid in each pair. 1. HNO 2 2. HBr 3. H 3 O +