1. Pg 569 - 581

2.  Amphoteric substance: can act as an acid or as a base ◦ Water is the most common amphoteric substance  Self-ionization of water: H 2 O(l) + H 2 O(l) H 3 O + (aq) + OH - (aq)

3.  At 25 o C actual concentrations are: ◦ [H 3 O + ] = [OH - ] = 1.0 x 10 -7 M  The product of the two concentrations is: ◦ [H 3 O + ]*[OH - ] = 1.0 x 10 -14 @ 25 o C  We call this K w  To simplify the equation, we write H 3 O + as H +  K w = [H + ]*[OH - ] = 1.0 x 10 -14 @ 25 o C

4.  Kw = ion-proton constant ◦ In any aqueous solution at 25 o C, no matter what it contains, the product of [H + ] and [OH - ] must ALWAYS equal 1.0 x 10 -14  What will happen if the concentration of H + increases? If it decreases? ◦ If [H + ] increases, [OH - ] decreases ◦ If [H + ] decreases, [OH - ] increases

5. 1. [H + ] = [OH - ] neutral 2. [H + ] > [OH - ] acidic 3. [H + ] < [OH - ] basic Remember: [H + ]*[OH - ] = 1 x 10 -14

6. Calculate [H + ] or [OH - ] as required for each of the following solutions at 25 °C, and state whether the solution is neutral, acidic, or basic. a)1.0 x 10 -5 M OH - b)1.0 x 10 -7 M OH - c)10.0 M H + H+ = 1.0 x 10 -9 M, basic H+ = 1.0 x 10 -7 M, neutral OH- = 1.0 x 10 -15 M, acidic Calculate [H+] in a solution in which [OH-] = 2.0 x 10 -2 M. Is this solution acidic, neutral or basic?  5.0 x 10 -13 M, basic

7.  pH measures the “power” of the hydrogen ion ◦ “Power” refers to exponent of 10 ◦ Based on the base 10 log scale.  pH = -log[H + ]  If [H + ]= 1.00 x 10 -7, pH = ?  If [H + ]= 1.00 x 10 -2, pH = ?  [H+] = inverse log (-pH)  If pH = 9, [H + ]=?  If a solution has a pH of 2, how much more acidic is it than a solution with a pH of 4?  100 times more acidic!!

8. Try the following: 1. Find pH if [H + ] = 3.5 x 10 -3 Find pH if [OH - ] = 1.4 x 10 -3 2. If the pH = 9.4 what is [H + ] ? If the pH = 4.9 what is [OH - ] ? Answers: 1) 2.452) 11.15 3) 4.0 x 10 -10 4) 7.9 x 10 -10

10.  pOH = -log[OH - ]  If pH = 5, What would pOH be?  pH + pOH = 14.00

11. 1. The pOH of a solution is 5.67. What is the [OH - ] of the solution? What is the [H + ]? 2. The [OH - ] of drain cleaner is 3.2 x 10 -11 M. What is the pOH? The pH? Is it acidic, basic or neutral? 1)2.1 x 10 -6 M and 4.8 x 10 -9 M 2)10.50 and 3.50 = acidic!!