1. Acids Acids: produce H + ions Example: Taste sour Can burn Turn litmus paper red Naming Acids: 1 “hydro-” + Nonmetal element root + “-ic” acid Example: Hydrochloric acid HCl (g) H + (aq) + Cl - (aq)

2. Bases Bases: donate OH - ions Example: Taste bitter Feel soapy Turn litmus paper blue Hydroxide ions with group 1A or 2A metals 2 NaOH (s) Na + (aq) + OH - (aq)

3. Acids & Bases Bronsted-Lowry Acids: donate a proton HCl + H 2 O  H 3 O + + Cl - Bronsted-Lowry Bases: accept a proton N H 3 + H 2 O  NH 4 + + OH - Conjugate acid-base pairs: one loses a proton, other gains a proton 3 A - is the conjugate base of HABH + is the conjugate acid of B HAHA+B+A-BH+BH+ H + donor H + acceptor H + acceptor

4. Acids & Bases 4

5. Strengths of Acids & Bases Strong acids & strong bases: –dissociate completely in water –only forward reaction Weak acids & weak bases: –Dissociate slightly in water –Both forward and reverse reactions 5 H2OH2O++NH 3 NH 4 + OH - Reaction will favor side with weaker acid and weaker base Water is a weaker acid than NH 4 + acid base NH 3 is a weaker base than OH -

6. Strengths of Acids & Bases 6

7. Dissociation Constants Equilibrium constants for weak acids and bases 7 H 2 O (l)++HA (aq)H 3 O + (aq)A - (aq)

8. Ionization of Water Water is amphoteric 8 H 2 O (l)+H 3 O + (aq)OH - (a q) 2 In pure water: Dissociation constant for water? K w =[H 3 O + ] [OH - ] =1.0 x 10 -14 M [H 3 O + ] = [OH - ]= 1.0 x 10 -7 M

9. Ionization of Water Calculate the concentration of hydroxide ions in coffee, an aqueous solution containing 1.0 x 10 -5 M H 3 O + ions 9 Calculate the concentration of hydroxide ions in milk, which contains 5.0 x 10 -7 M H 3 O + ions

10. The pH Scale Scale from 0 to 14 Acidic Neutral Basic 10 pH < 7[H 3 O + ] > 1.0 x 10 -7 M pH = 7[H 3 O + ] = 1.0 x 10 -7 M pH > 7[H 3 O + ] < 1.0 x 10 -7 M pH = -log[H 3 O + ] Milk: [H 3 O + ] = 5.0 x 10 -7 M pH of milk = -log[H 3 O + ] =-log[ 5.0 x 10 -7 M ]= 6.3

11. The pH Scale 11

12. Practice problem? Calculate the pH of a solution that has… [H 3 O + ] = 1.0 x 10 -8 M [OH-] = 4.0 x 10 -2 M 12