1. ANNOUNCEMENTS Arnold Orville Beckman (April 10, 1900 – May 18, 2004) Invented the pH meter in 1934 (because of lemons!) Founded Silicon Valley (located in Palo Alto so that it was near his friend’s aging mother) Was a Marine in WWI

2. Water autoionization

4. pH and pOH calculations What is the pH of [H 3 O + ] = 4.6 x 10 -5 ? What is the pOH of [OH - ] = 3.3 x 10 -4 ? What is the pOH of [H 3 O + ] = 4.6 x 10 -5 ? What is the [H 3 O + ] when the pH = 4.2? [H 3 O + ][OH - ] = 1.0 x 10 -14 pH = -log[H 3 O + ] pOH = -log[OH - ] [H 3 O + ] = 10 -pH [OH - ] = 10 -pH pH + pOH = 14.00

5. [H 3 O + ]pH [OH - ]pOH pH+pOH=14 [H 3 O + ]][OH - ]=10 -14 The pH Square

6. What is the pH when [H 3 O + ] = 0.045 M? 1. 0.045 2. 13.995 3. -1.35 4. 1.35

7. What is the pH when [OH - ] = 6.5 x 10 -4 M? 1. 3.18 2. -3.18 3. 10.81 4. 15.18

8. What is the [OH-] when pH = 5.84 M? What is the [OH - ] when pH = 5.84 M? 1. 1.45 x 10 8 2. 3.31 x 10 -6 3. 6.92 x 10 -9 4. 5.84

9. Strong acids and bases ionize completely Strong monoprotic acids [H 3 O + ] = [acid] Strong diprotic acid [H 3 O + ] = 2[acid] Strong monoprotic base [OH - ] = [base] Strong diprotic base [OH - ] = 2[base]

10. Calculating the pH of a strong acid solution What is the pH of a 0.150 M solution of HCl?

11. Changing the pH of a solution is harder the farther away you are from neutral pH How much acid does it take to go from pH=1 to pH=2? How much acid does it take to go from pH=5 to pH=6? HCl molar mass=36.46 g/mol

12. What is the real range of pH’s that are possible? Can pH be zero? Can pH be negative? Can pH be greater than 14?

13. Conjugate Acid-Base Pairs Different definitions of acids and bases Brønsted-Lowry ◦ Acid = H + (proton) donor ◦ Base = H + (proton) acceptor ◦ Acid-base reaction involves proton transfer ◦ Conjugate acid/base = what is left on the other side after the proton has been transferred AcidConjugate base HFF-F- NH 4 + NH 3

14. What is the conjugate base of CH 3 CO 2 H? 1. CH 3 CO 2 H 2 2. CH 3 CO 2 - 3. CH 3 CO 3

15. What is the conjugate acid of HPO 4 2-? What is the conjugate acid of HPO 4 2- ? 1. H 2 PO 4 - 2. H 3 PO 4 3. PO 4 3-

16. Lab Information-pH titration

17. Acid (or base) strength depends on the equilibrium constant

19. pH Measurements are used to determine acid strength (K a ) A 0.10M solution of oxalic acid has a pH of 1.48. What is the K a value for oxalic acid?

20. What is the value of K a for an acid, HA, for which a 0.240 M solution has a pH of 3.28? Is this acid stronger or weaker than oxalic acid? (K a =0.016)

21. Determining K b from pH data A 0.300 M solution of a weak base has a pH of 9.20. What is K b ?

22. Have a great weekend!