1. HL Acids and Bases

2. Strength of Acids/Bases Strong Acids (100% ionized or dissociated) – HCl – HBr – HI – HNO 3 – H 2 SO 4 – HClO 4 – HClO 3 Strong bases (100% ionized or dissociated) – Hydroxides of column 1A and 2A Ca(OH) 2 and below Be sure you can write the reaction of a strong acid or base with water

3. Autoionization of Water [287-290] Bronsted-Lowry acid/base behavior takes place in aqueous solutions Water acts as both an acid and a base 2 H 2 O  H 3 O + + OH – Ion product of water is (equilibrium constant) K w = [OH - ][H 3 O + ] = 1.0 x 10 -14 M 2 at 25  C

4. Autoionization of Water [287-290] Changes in temperature will affect the value of K w and the concentrations of H 3 O + and OH – Because the ionization of water involves breaking bonds, the forward reaction is endothermic Raising the temperature will shift the equilibrium to the right and increase the value of the equilibrium constant

5. Autoionization of Water [287-290] pH of water is always neutral, but not always equal to 7 Neutral is [OH - ] = [H 3 O + ]

6. pH scale [289] pH is an abbreviation for “power of hydrogen, pH is a logarithmic scale. pH = - log [H 3 O + ] pOH = - log [OH - ] pH + pOH = 14 K w = [OH - ][H 3 O + ] = 1.0 X 10 -14 [H 3 O + ] = 10 -pH [OH - ] = 10 -pOH

7. pH of Strong Acids/Bases [290-291] Once you know the [H + ] of any acid or base, you can easily determine the pH Strong acids are 100% dissociated – [H + ] = [HA] where HA = acid Strong bases are 100% dissociated – [OH - ] = [MOH] where MOH = metal hydroxide – Be careful with M(OH) 2

8. pH of Strong Acids/Bases[290-291] Exercises 19-22 page 291 Examples: find the pH of 0.0075 M HNO 3 0.05 M Ba(OH) 2

9. pH of Weak Acids/Bases [291-298] Weak acids and bases are less than 100% dissociated, they exist in equilibrium HA + H 2 O  A - + H 3 O + K a = [H 3 O + ][A - ] [HA] A - + H 2 O  HA + OH - K b = [OH - ][HA] [A - ]

10. pH of Weak Acids/Bases [291-298] The larger the value of the K a, the stronger the acid The larger the value of the K b, the stronger the base Exercises 23-25 page 293

11. pH of Weak Acids/Bases [291-298] Worked examples pages 294-295

12. pH of Weak Acids/Bases [291-298] K a x K b = K w = 1 x 10 -14 pK a = -log K a pK b = -log K b pK a + pK b = 14 The larger the pKa, the weaker the acid The larger the pKb, the weaker the base

13. pH of Weak Acids/Bases [291-298] Exercises 29-31 page 297 Exercises 32-33 page 298

14. pH of Weak Acids/Bases [291-298] Harder examples 1)What is the pH of a 0.0500 M solution of weak acid (pK a = 3.40)? 2)Calculate the pH of a 0.00338 M solution of fluoride ion. 3)Calculate the pH of a 0.100 M solution of carbonate ion.

15. Buffer Solutions [299-301] A buffer solution is resistant to changes in pH upon addition of small amounts of acid or base.

16. Buffer Solutions [299-301] An acidic buffer solution consists of a weak acid and a salt of its conjugate base http://www.youtube.com/watch?v=l9dliAngF2k&feat ure=relmfu http://www.youtube.com/watch?v=l9dliAngF2k&feat ure=relmfu

17. Buffer Solutions [299-301] An basic buffer solution consists of a weak base and a salt of its conjugate acid

18. pH of Buffer Solutions [302-303] Henderson-Hasselbalch equation

19. pH of Buffer Solutions [302-303] What is the pH of a buffer prepared from 0.200 M ethanoic acid and 0.0500 M sodium ethanoate? Calculate the pH of a buffer solution at 298K, prepared by mixing 25 ml of 0.20 M HF with 52 mL 0.10 M NaF. Calculate the pH of a buffer solution at 298K, prepared by mixing 25 ml of 0.10 M ethanoic acid with 25 mL 0.10 M sodium ethanoate.

20. Preparation of Buffer Solutions [303-305] A buffer may not always look like a buffer Example would be a weak acid added to a strong base 25 mL of 0.1 M acetic acid is added to 13 mL of 0.1M NaOH. What is the pH?

21. Preparation of Buffer Solutions [303-305] Let’s look at different ways to prepare a buffer

22. Preparation of Buffer Solutions [303-305] Exercises 34-36 page 305

23. Acid-Base Properties of Salts [305-307] An aqueous salt solution can be neutral, acidic, or basic In order for a salt to have acid/base properties, the cation or anion must be able to hydrolyze water Hydrolysis is the reaction of a substance with water that produces H+ and OH- ions

24. Acid-Base Properties of Salts [305-307] Cation and anion from strong acid and base – NaCl, KBr, CaSO 4 – Cation or anion does not hydrolyze water – pH is neutral (=7)

25. Acid-Base Properties of Salts [305-307] Cation from strong base, anion from weak acid – NaF, KOOCCH 3, – pH is basic (>7)

26. Acid-Base Properties of Salts [305-307] Cation from weak base, anion from strong acid – NH 4 Cl – pH is acidic (<7)

27. Acid-Base Properties of Salts [305-307] Cation from weak base, anion from weak acid – NH 4 CN – pH depends on which is strongest

28. Acid-Base Properties of Salts [305-307] Exercises 37-39 page 307

29. Acid/Base Titrations [307-312] Titration (Chemistry) an operation, used in volumetric analysis, in which a measured amount of one solution is added to a known quantity of another solution until the reaction between the two is complete. – Neutralization is the outcome of an acid/base titration – Neutralization occurs at the endpoint or equivalence point – Titration can be used to determine the concentration of a solution

30. Acid/Base Titrations [307-312]

31. Strong acid with a strong base [309-310] 1 2 3 4

33. Strong base with a strong acid

34. Weak acid with strong base [310] ½ equivalence point pH = pK a 1 2 3 4

35. Weak acid with strong base [310]

36. Weak base with strong acid [311] 1 2 4 3

38. Indicators [312-315] An indicator is a weak acid HIn  H + + In- Color 1 Color 2 Indicators are different colors depending on pH Like a buffer, an indicator is only useful over a limited range Indicator will change color when pH is equal to its pKa

40. Indicators [312-315] Exercises 43-44 page 315 For which of the following titrations would phenolphthalein be the least appropriate indicator? 1)Nitric acid and sodium hydroxide 2)Sulfuric acid and ammonia 3)Ethanoic acid and barium hydroxide 4)Hydrochloric acid and potassium hydroxide