1. Acids & Bases pH

2. Ionization of Water H 2 O + H 2 O H 3 O + + OH - K w = [H 3 O + ][OH - ] = 1.0  10 -14 Kw=ionization constant for H2O

3. Acidic or Basic [H 3 O + ][OH - ] = 1.0  10 -14  ACIDIC [H+] is greater than [OH-] [H+] is greater than 1.0  10 -7  BASIC [OH-] is greater than [H+] [H+] is less than 1.0  10 -7

4. Ionization of Water  Find the hydroxide ion concentration of 3.0  10 -2 M HCl. [H 3 O + ][OH - ] = 1.0  10 -14 [3.0  10 -2 ][OH - ] = 1.0  10 -14 [OH - ] = 3.3  10 -13 M Acidic or basic? Acidic ([H+] > 1 EE -7)

5. Problem  Colas are slightly acidic. If the [H+] in a solution is 1.0 x 10 -5 M, is the solution acidic basic or neutral? What is the [OH-] of this solution? Known: [H+] = 1.0 x 10 -5 M Kw = [H+] x [OH-] = 1 x 10 -14 Answer 1: Because 1.0 x 10 -5 M is greater than 1.0 x 10 -7 M, the solution is acidic Answer 2: [OH-] = 1 x 10 -14 1.0 x 10 -5 = 1.0 x 10 -9 M

6. pH = -log [H + ] pH Scale 0 7 INCREASING ACIDITY NEUTRAL INCREASING BASICITY 14

7. pH Scale pH of Common Substances

8. pH Scale pH = -log [H + ] pOH = -log [OH - ] pH + pOH = 14 [ ] = concentration

9. pH Scale  What is the pH of 0.050 M HNO 3 ? pH = -log[H + ] pH = -log[0.050] pH = 1.3 Acidic or basic? Acidic

10. pH Scale  What is the molarity (conc) of HBr in a solution that has a pOH of 9.6? pH + pOH = 14 pH + 9.6 = 14 pH = 4.4 Acidic pH = -log[H + ] 4.4 = -log[H + ] - 4.4 = log[H + ] - 4.4 (10 x key)= [H + ] [H + ] = 4.0  10 -5 M HBr