1. Acids, Bases, and pH

2. Acids and Bases Acids produce H + ions Bases produce OH - ions

3. Macroscopic properties of acids and bases Taste and feel – Acids taste sour (lemon juice, vinegar) – Bases taste bitter – Bases are slippery (soap)

4. Litmus test and other color changes – Indicators change colors in the presence of an acid or a base – Litmus: acid = red, base = blue

6. Submicroscopic behavior of acids Hydrogen ion formation HCl  H + + Cl - HNO 3  H + + NO 3 -

7. Acidic hydrogen atoms – Reaction of acid with water is a transfer of a hydrogen ion from an acid to a water molecule – Any hydrogen that can be transferred to water is called an acidic hydrogen – It is possible for acids to have more than one acidic hydrogen

10. Acids are electrolytes – Substance that dissolve in pure water to form ions & conduct electricity – Not all acids conduct electricity equally well Strong acids conduct electricity better than weak acids

12. Submicroscopic behavior of bases Hydroxide ion formation can happen two ways Simple bases: NaOH  Na + + OH - Bases that accept H + (Bronsted-Lowry): NH 3 + H 2 O  NH 4 + +OH -

13. Bases are electrolytes – Strong bases conduct electricity better than weak bases

14. Strengths of Acids and Bases Strong acids and bases ionize completely while weak acids and bases ionize only partially

15. Strong Bases A base that completely dissociates into ions when dissolved in water Ionic compounds that contain hydroxide ions NaOH  Na + + OH -

16. Strong Acids An acid that completely ionizes in water HCl  H + + Cl -

18. Weak Acids An acid that only partially ionizes in solution Usually when acidic hydrogen is bonded to an oxygen H 2 CO 3  H + + CO 3 2- + H 2 CO 3

20. Weak Bases Only partially ionize in solution NH 3 + H 2 O  NH 4 + + OH - + NH 3 + H 2 O

21. Types of Acid-Base Reactions Neutralization reaction – properties of both acid and base are neutralized when they react Acid + Base  Salt + Water – Salt – ionic compound (metal + nonmetal)

23. Strong Acid + Strong Base Strong acids completely ionize Strong bases completely ionize

24. Ionic equation – everything (aq) written as ions – Spectator ions – Net ionic equation NaOH (aq) + HCl (aq)  NaCl(aq) + H 2 O(l)

25. H 2 SO 4 (aq) + 2KOH(aq)  K 2 SO 4 (aq) + H 2 O(l)

26. Strong acid + strong base & pH – Hydrogen ion from acid and hydroxide ion from base form water which has a pH of 7

27. Strong Acid + Weak Base Weak bases do not completely ionize 3HBr(aq) + Al(OH) 3 (s)  AlBr 3 (aq) + H 2 O(l)

28. Weak Acid & Strong Base HC 2 H 3 O 2 (aq) + NaOH  NaC 2 H 3 O 2 + H 2 O

29. Weak is not insignificant Most acids and bases are classified as weak Most of the acid-base chemistry in living systems occurs between weak acids and weak bases

30. Strength is not concentration Weak & strong compare strength Dilute and concentrated compare concentration Combination of strength and concentration determine the behavior of solution

31. The pH Scale A mathematical scale in which the concentration of H + ions in a solution is expressed as a number from 0 – 14

32. Interpreting the pH scale pH < 7 = acidic pH = 7 = neutral pH > 7 = basic Each unit of pH represents a power of 10 – Something with pH of 2 is 10 times more acidic than something with a pH of 3

33. pH = -log [H + ] What is the pH of solutions having the following ion concentrations? 1.[H + ] = 1.0 x 10 -2 M 2.[H + ] = 3.0 x 10 -6 M

34. Relating H + and OH - ion concentration [H + ][OH - ] = 1 x 10 -14 As [H + ] increases what happens to [OH - ]?

37. Calculate the [H + ] or [OH  ] and state whether the solution is neutral, acidic, or basic – 1.0 x 10 -5 M OH - – 1.0 x 10 -7 M OH - – 10.0 M H +

38. pOH = -log [OH - ] What is the pOH of a solution having the following ion concentration? 1.[OH - ] = 1.0 x 10 -6 M 2.[OH - ] = 6.5 x 10 -4 M

39. pH + pOH = 14 What is the pOH of a solution whose pH is 5? What is the pH of a solution whose [OH - ] = 4.0 x 10 -3 M

40. Calculate the pH and pOH of the following solutions: 1.[H+] = 0.000033 M 2.[OH-] = 0.0095 M

41. Bronsted-Lowry Acids & Bases Acid – H + donor Base – H + acceptor HC 2 H 3 O 2 + NH 3  NH 4 + + C 2 H 3 O 2 -

42. Conjugate base – formed when acid donates proton Conjugate acid – formed when base accepts a proton HC 2 H 3 O 2 + NH 3  NH 4 + + C 2 H 3 O 2 -

43. Identify the acid, base, conjugate acid, and conjugate base in the following: HCO 3 -1 + H 2 O  CO 3 -2 + H 3 O +1

44. Applications of Acid-Base Reactions Buffers regulate pH – Solution that resist changes in pH when moderate amounts of acids or bases are added – Prepared by using a weak acid and its conjugate base or weak base and its salt

46. Acid-Base Chemistry & Antacids pH of stomach acid = 2.5 Stomach is coated with basic mucous to protect it If stomach becomes too acidic mucous layer breaks down by acid-base neutralization Antacids are bases

48. Acid-Base Titrations Titration – process of determining molarity of an acid or a base through the use of an acid- base reaction – Molarity of one of the reactants is known but the other is unknown – Standard solution – solution whose molarity is known

49. Standard solution is loaded into a buret – Allows an accurate measurement of the delivery of a given volume of liquid

50. Using indicators – when solution is neutral you know you have added exactly enough stock solution to react with the unknown solution – endpoint

51. A 15.0 mL sample of a solution of H 2 SO 4 with unknown molarity is titrated with 32.4 mL of 0.145 M NaOH to the endpoint. What is the molarity of the sulfuric acid solution?