1. 1 © 2006 Brooks/Cole - Thomson Chemistry and Chemical Reactivity 6th Edition John C. Kotz Paul M. Treichel Gabriela C. Weaver CHAPTER 17 Principles of Reactivity: Chemistry of Acids and Bases © 2006 Brooks/Cole Thomson Lectures written by John Kotz

2. 2 © 2006 Brooks/Cole - Thomson The Chemistry of Acids and Bases Chapter 17

3. 3 © 2006 Brooks/Cole - Thomson Acid and Bases

4. 4 © 2006 Brooks/Cole - Thomson Acid and Bases

5. 5 © 2006 Brooks/Cole - Thomson Acid and Bases

6. 6 © 2006 Brooks/Cole - Thomson Strong and Weak Acids/Bases Generally divide acids and bases into STRONG or WEAK ones.Generally divide acids and bases into STRONG or WEAK ones. STRONG ACID: HNO 3 (aq) + H 2 O(liq) --- >H 3 O + (aq) + NO 3 - (aq) HNO 3 is about 100% dissociated in water.

7. 7 © 2006 Brooks/Cole - Thomson HNO 3, HCl, H 2 SO 4 and HClO 4 are among the only known strong acids. Strong and Weak Acids/Bases

8. 8 © 2006 Brooks/Cole - Thomson Weak acids are much less than 100% ionized in water.Weak acids are much less than 100% ionized in water. One of the best known is acetic acid = CH 3 CO 2 H Strong and Weak Acids/Bases

9. 9 © 2006 Brooks/Cole - Thomson Strong Base: 100% dissociated in water.Strong Base: 100% dissociated in water. NaOH(aq) ---> Na + (aq) + OH - (aq) NaOH(aq) ---> Na + (aq) + OH - (aq) Strong and Weak Acids/Bases Other common strong bases include KOH and Ca(OH) 2. CaO (lime) + H 2 O --> Ca(OH) 2 (slaked lime) Ca(OH) 2 (slaked lime) CaO

10. 10 © 2006 Brooks/Cole - Thomson Weak base: less than 100% ionized in waterWeak base: less than 100% ionized in water One of the best known weak bases is ammonia NH 3 (aq) + H 2 O(liq)   NH 4 + (aq) + OH - (aq) Strong and Weak Acids/Bases

11. 11 © 2006 Brooks/Cole - Thomson ACID-BASE THEORIES The most general theory for common aqueous acids and bases is the BRØNSTED - LOWRY theoryThe most general theory for common aqueous acids and bases is the BRØNSTED - LOWRY theory ACIDS DONATE H + IONSACIDS DONATE H + IONS BASES ACCEPT H + IONSBASES ACCEPT H + IONS

12. 12 © 2006 Brooks/Cole - Thomson ACID-BASE THEORIES NH 3 is a BASE in water — and water is itself an ACID NH 3 / NH 4 + is a conjugate pair — related by the gain or loss of H + Every acid has a conjugate base - and vice-versa.

13. 13 © 2006 Brooks/Cole - Thomson The Brønsted definition means NH 3 is a BASE in water — and water is itself an ACID ACID-BASE THEORIES

14. 14 © 2006 Brooks/Cole - Thomson Conjugate Pairs

15. 15 © 2006 Brooks/Cole - Thomson More About Water H 2 O can function as both an ACID and a BASE. In pure water there can be AUTOIONIZATION Equilibrium constant for autoionization = K w K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 at 25 o C

16. 16 © 2006 Brooks/Cole - Thomson More About Water K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 at 25 o C In a neutral solution [H 3 O + ] = [OH - ] so K w = [H 3 O + ] 2 = [OH - ] 2 and so [H 3 O + ] = [OH - ] = 1.00 x 10 -7 M Autoionization

17. 17 © 2006 Brooks/Cole - Thomson Calculating [H 3 O + ] & [OH - ] You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [HO + ] and [OH - ]. You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [H 3 O + ] and [OH - ].Solution 2 H 2 O(liq)   HO + (aq) + OH - (aq) 2 H 2 O(liq)   H 3 O + (aq) + OH - (aq) Le Chatelier predicts equilibrium shifts to the ____________. [HO + ] < 10 -7 at equilibrium. [H 3 O + ] < 10 -7 at equilibrium. Set up a ICE table.

18. 18 © 2006 Brooks/Cole - Thomson Calculating [H 3 O + ] & [OH - ] You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [HO + ] and [OH - ]. You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [H 3 O + ] and [OH - ].Solution 2 H 2 O(liq)   H 3 O + (aq) + OH - (aq) initial00.0010 initial00.0010 change+x+x change+x+x equilibx0.0010 + x equilibx0.0010 + x K w = (x) (0.0010 + x) Because x << 0.0010 M, assume [OH - ] = 0.0010 M [H 3 O + ] = K w / 0.0010 = 1.0 x 10 -11 M

19. 19 © 2006 Brooks/Cole - Thomson Calculating [H 3 O + ] & [OH - ] You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [HO + ] and [OH - ]. You add 0.0010 mol of NaOH to 1.0 L of pure water. Calculate [H 3 O + ] and [OH - ].Solution 2 H 2 O(liq)   HO + (aq) + OH - (aq) 2 H 2 O(liq)   H 3 O + (aq) + OH - (aq) [HO + ] = K w / 0.0010 = 1.0 x 10 -11 M [H 3 O + ] = K w / 0.0010 = 1.0 x 10 -11 M This solution is _________ because [H 3 O + ] < [OH - ]

20. 20 © 2006 Brooks/Cole - Thomson [H 3 O + ], [OH - ] and pH A common way to express acidity and basicity is with pH pH = log (1/ [H 3 O + ]) = - log [H 3 O + ] In a neutral solution, [HO + ] = [OH - ] = 1.00 x 10 -7 at 25 o C In a neutral solution, [H 3 O + ] = [OH - ] = 1.00 x 10 -7 at 25 o C pH = -log (1.00 x 10 -7 ) = - (-7) = 7

21. 21 © 2006 Brooks/Cole - Thomson [H 3 O + ], [OH - ] and pH What is the pH of the 0.0010 M NaOH solution? [HO + ] = 1.0 x 10 -11 M [H 3 O + ] = 1.0 x 10 -11 M pH = - log (1.0 x 10 -11 ) = 11.00 General conclusion — Basic solution pH > 7 Basic solution pH > 7 Neutral pH = 7 Neutral pH = 7 Acidic solutionpH < 7 Acidic solutionpH < 7

22. 22 © 2006 Brooks/Cole - Thomson The pH Scale Active Figure 17.2

23. 23 © 2006 Brooks/Cole - Thomson [H 3 O + ], [OH - ] and pH If the pH of Coke is 3.12, it is ____________. Because pH = - log [HO + ] then Because pH = - log [H 3 O + ] then log [HO + ] = - pH log [H 3 O + ] = - pH Take antilog and get [HO + ] = 10 -pH [H 3 O + ] = 10 -pH [HO + ] = 10 -3.12 = 7.6 x 10 -4 M [H 3 O + ] = 10 -3.12 = 7.6 x 10 -4 M

24. 24 © 2006 Brooks/Cole - Thomson pH of Common Substances

25. 25 © 2006 Brooks/Cole - Thomson Other pX Scales In generalpX = -log X and so pOH = - log [OH - ] K w = [HO + ] [OH - ] = 1.00 x 10 -14 at 25 o C K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 at 25 o C Take the log of both sides -log (10 -14 ) = - log [HO + ] + (-log [OH - ]) -log (10 -14 ) = - log [H 3 O + ] + (-log [OH - ]) pK w = 14 = pH + pOH pK w = 14 = pH + pOH

26. 26 © 2006 Brooks/Cole - Thomson Equilibria Involving Weak Acids and Bases Aspirin is a good example of a weak acid, K a = 3.2 x 10 -4

27. 27 © 2006 Brooks/Cole - Thomson Equilibria Involving Weak Acids and Bases AcidConjugate Base AcidConjugate Base acetic, CH 3 CO 2 HCH 3 CO 2 -, acetate ammonium, NH 4 + NH 3, ammonia bicarbonate, HCO 3 - CO 3 2-, carbonate A weak acid (or base) is one that ionizes to a VERY small extent (< 5%).

28. 28 © 2006 Brooks/Cole - Thomson Equilibria Involving Weak Acids and Bases Consider acetic acid, CH 3 CO 2 H (HOAc) HOAc + H 2 O   H 3 O + + OAc - Acid Conj. base (K is designated K a for ACID) Because [H 3 O + ] and [OAc - ] are SMALL, K a << 1.

29. 29 © 2006 Brooks/Cole - Thomson Equilibrium Constants for Weak Acids Weak acid has K a < 1 Leads to small [H 3 O + ] and a pH of 2 - 7

30. 30 © 2006 Brooks/Cole - Thomson Equilibrium Constants for Weak Bases Weak base has K b < 1 Leads to small [OH - ] and a pH of 12 - 7

31. 31 © 2006 Brooks/Cole - Thomson Ionization Constants for Acids/Bases Acids ConjugateBases Increase strength

32. 32 © 2006 Brooks/Cole - Thomson Relation of K a, K b, [H 3 O + ] and pH

33. 33 © 2006 Brooks/Cole - Thomson K and Acid-Base Reactions Reactions always go from the stronger A-B pair (larger K) to the weaker A-B pair (smaller K). ACIDSCONJUGATE BASES STRONG weak weak STRONG

34. 34 © 2006 Brooks/Cole - Thomson K and Acid-Base Reactions A strong acid is 100% dissociated. Therefore, a STRONG ACID —a good H + donor— must have a WEAK CONJUGATE BASE —a poor H + acceptor. HNO 3 (aq) + H 2 O(liq)   H 3 O + (aq) + NO 3 - (aq) HNO 3 (aq) + H 2 O(liq)   H 3 O + (aq) + NO 3 - (aq) STRONG A base acid weak B STRONG A base acid weak B Every A-B reaction has two acids and two bases.Every A-B reaction has two acids and two bases. Equilibrium always lies toward the weaker pair.Equilibrium always lies toward the weaker pair. Here K is very large.Here K is very large. Every A-B reaction has two acids and two bases.Every A-B reaction has two acids and two bases. Equilibrium always lies toward the weaker pair.Equilibrium always lies toward the weaker pair. Here K is very large.Here K is very large.

35. 35 © 2006 Brooks/Cole - Thomson K and Acid-Base Reactions We know from experiment that HNO 3 is a strong acid. 1.It is a stronger acid than H 3 O + 2.H 2 O is a stronger base than NO 3 - 3.K for this reaction is large

36. 36 © 2006 Brooks/Cole - Thomson K and Acid-Base Reactions Acetic acid is only 0.42% ionized when [HOAc] = 1.0 M. It is a WEAK ACID HOAc + H 2 O   H 3 O + + OAc - WEAK A base acid STRONG B Because [H 3 O + ] is small, this must mean 1.H 3 O + is a stronger acid than HOAc 2.OAc - is a stronger base than H 2 O 3.K for this reaction is small

37. 37 © 2006 Brooks/Cole - Thomson Types of Acid/Base Reactions Strong acid (HCl) + Strong base (NaOH) H + + Cl - + Na + + OH -  H 2 O + Na + + Cl - Net ionic equation H + (aq) + OH - (aq)  H 2 O(liq) K = 1/K w = 1 x 10 14 Mixing equal molar quantities of a strong acid and strong base produces a neutral solution.

38. 38 © 2006 Brooks/Cole - Thomson Types of Acid/Base Reactions Weak acid (acetic ac.) + Strong base (NaOH) CH 3 CO 2 H + OH -   H 2 O + CH 3 CO 2 - This is the reverse of the reaction of CH 3 CO 2 - (conjugate base) with H 2 O.This is the reverse of the reaction of CH 3 CO 2 - (conjugate base) with H 2 O. OH - stronger base than CH 3 CO 2 -OH - stronger base than CH 3 CO 2 - K = 1/K b = 1/(5.6 x 10 -10 ) = 1.8 x 10 9K = 1/K b = 1/(5.6 x 10 -10 ) = 1.8 x 10 9 Mixing equal molar quantities of a weak acid and strong base produces the acid’s conjugate base. The solution is basic.

39. 39 © 2006 Brooks/Cole - Thomson Types of Acid/Base Reactions Strong acid (HCl) + Weak base (NH 3 ) H 3 O + + NH 3   H 2 O + NH 4 + This is the reverse of the reaction of NH 4 + (conjugate acid of NH 3 ) with H 2 O. H 3 O + stronger acid than NH 4 + K = 1/K a = 1.8 x 10 9 Mixing equal molar quantities of a strong acid and weak base produces the bases’s conjugate acid. The solution is acid.

40. 40 © 2006 Brooks/Cole - Thomson Types of Acid/Base Reactions Weak acid + Weak base Product cation = conjugate acid of weak base.Product cation = conjugate acid of weak base. Product anion = conjugate base of weak acid.Product anion = conjugate base of weak acid. pH of solution depends on relative strengths of cation and anion.pH of solution depends on relative strengths of cation and anion.

41. 41 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Acid You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH. Step 1. Define equilibrium concs. in ICE table. [HOAc][H 3 O + ][OAc - ] [HOAc][H 3 O + ][OAc - ]initialchangeequilib

42. 42 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Acid You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH. Step 1. Define equilibrium concs. in ICE table. [HOAc][H 3 O + ][OAc - ] initial1.0000 change-x+x+x equilib1.00-xxx Note that we neglect [H 3 O + ] from H 2 O.

43. 43 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Acid Step 2. Write K a expression You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH. This is a quadratic. Solve using quadratic formula.

44. 44 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Acid Step 3. Solve K a expression You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH. First assume x is very small because K a is so small. Therefore, Now we can more easily solve this approximate expression.

45. 45 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Acid Step 3. Solve K a approximate expression You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH. x = [ H 3 O + ] = [ OAc - ] = [K a 1.00] 1/2 x = [ H 3 O + ] = [ OAc - ] = 4.2 x 10 -3 M pH = - log [ H 3 O + ] = -log (4.2 x 10 -3 ) = 2.37

46. 46 © 2006 Brooks/Cole - Thomson Weak Bases

47. 47 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Base You have 0.010 M NH 3. Calc. the pH. NH 3 + H 2 O   NH 4 + + OH - NH 3 + H 2 O   NH 4 + + OH - K b = 1.8 x 10 -5 Step 1. Define equilibrium concs. in ICE table [NH 3 ][NH 4 + ][OH - ] [NH 3 ][NH 4 + ][OH - ]initialchangeequilib

48. 48 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Base You have 0.010 M NH 3. Calc. the pH. NH 3 + H 2 O   NH 4 + + OH - NH 3 + H 2 O   NH 4 + + OH - K b = 1.8 x 10 -5 Step 1. Define equilibrium concs. in ICE table [NH 3 ][NH 4 + ][OH - ] [NH 3 ][NH 4 + ][OH - ] initial0.01000 change-x+x+x equilib0.010 - xx x

49. 49 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Base You have 0.010 M NH 3. Calc. the pH. NH 3 + H 2 O   NH 4 + + OH - NH 3 + H 2 O   NH 4 + + OH - K b = 1.8 x 10 -5 Step 2. Solve the equilibrium expression Assume x is small, so x = [OH - ] = [NH 4 + ] = 4.2 x 10 -4 M x = [OH - ] = [NH 4 + ] = 4.2 x 10 -4 M and [NH 3 ] = 0.010 - 4.2 x 10 -4 ≈ 0.010 M The approximation is valid!

50. 50 © 2006 Brooks/Cole - Thomson Equilibria Involving A Weak Base You have 0.010 M NH 3. Calc. the pH. NH 3 + H 2 O   NH 4 + + OH - NH 3 + H 2 O   NH 4 + + OH - K b = 1.8 x 10 -5 Step 3. Calculate pH [OH - ] = 4.2 x 10 -4 M so pOH = - log [OH - ] = 3.37 Because pH + pOH = 14, pH = 10.63

51. 51 © 2006 Brooks/Cole - Thomson MX + H 2 O ----> acidic or basic solution? Consider NH 4 Cl NH 4 Cl(aq) ----> NH 4 + (aq) + Cl - (aq) (a)Reaction of Cl - with H 2 O Cl - + H 2 O ---->HCl + OH - Cl - + H 2 O ---->HCl + OH - baseacidacidbase baseacidacidbase Cl - ion is a VERY weak base because its conjugate acid is strong. Therefore, Cl - ----> neutral solution Acid-Base Properties of Salts

52. 52 © 2006 Brooks/Cole - Thomson NH 4 Cl(aq) ----> NH 4 + (aq) + Cl - (aq) (b)Reaction of NH 4 + with H 2 O NH 4 + + H 2 O ---->NH 3 + H 3 O + NH 4 + + H 2 O ---->NH 3 + H 3 O + acidbasebaseacid acidbasebaseacid NH 4 + ion is a moderate acid because its conjugate base is weak. Therefore, NH 4 + ----> acidic solution See TABLE 17.4 for a summary of acid-base properties of ions. Acid-Base Properties of Salts

53. 53 © 2006 Brooks/Cole - Thomson Acid-Base Properties of Salts

54. 54 © 2006 Brooks/Cole - Thomson Calculate the pH of a 0.10 M solution of Na 2 CO 3. Na + + H 2 O ---> neutral CO 3 2- +H 2 O   HCO 3 - + OH - baseacid acidbase K b = 2.1 x 10 -4 K b = 2.1 x 10 -4 Step 1.Set up ICE table [CO 3 2- ][HCO 3 - ][OH - ] initial [CO 3 2- ][HCO 3 - ][OH - ] initial change equilib equilib Acid-Base Properties of Salts

55. 55 © 2006 Brooks/Cole - Thomson Step 1.Set up ICE table [CO 3 2- ][HCO 3 - ][OH - ] initial0.1000 [CO 3 2- ][HCO 3 - ][OH - ] initial0.1000 change-x+x+x equilib0.10 - xxx equilib0.10 - xxx Acid-Base Properties of Salts Calculate the pH of a 0.10 M solution of Na 2 CO 3. Na + + H 2 O ---> neutral CO 3 2- +H 2 O Æ HCO 3 - +OH - baseacid acidbase K b = 2.1 x 10 -4 K b = 2.1 x 10 -4

56. 56 © 2006 Brooks/Cole - Thomson Calculate the pH of a 0.10 M solution of Na 2 CO 3. Na + + H 2 O ---> neutral CO 3 2- +H 2 O   HCO 3 - +OH - baseacid acidbase K b = 2.1 x 10 -4 K b = 2.1 x 10 -4 Acid-Base Properties of Salts Assume 0.10 - x ≈ 0.10, because 100K b < C o x = [HCO 3 - ] = [OH - ] = 0.0046 M Step 2.Solve the equilibrium expression

57. 57 © 2006 Brooks/Cole - Thomson Calculate the pH of a 0.10 M solution of Na 2 CO 3. Na + + H 2 O ---> neutral CO 3 2- +H 2 O   HCO 3 - +OH - baseacid acidbase K b = 2.1 x 10 -4 K b = 2.1 x 10 -4 Acid-Base Properties of Salts Step 3.Calculate the pH [OH - ] = 0.0046 M pOH = - log [OH - ] = 2.34 pH + pOH = 14, so pH = 11.66, and the solution is ________.

58. 58 © 2006 Brooks/Cole - Thomson Lewis acid a substance that accepts an electron pair Lewis Acids & Bases Lewis base a substance that donates an electron pair

59. 59 © 2006 Brooks/Cole - Thomson Reaction of a Lewis Acid and Lewis Base New bond formed using electron pair from the Lewis base.New bond formed using electron pair from the Lewis base. Coordinate covalent bondCoordinate covalent bond Notice geometry change on reaction.Notice geometry change on reaction.

60. 60 © 2006 Brooks/Cole - Thomson Formation of hydronium ion is also an excellent example. Lewis Acids & Bases Electron pair of the new O-H bond originates on the Lewis base.Electron pair of the new O-H bond originates on the Lewis base.

61. 61 © 2006 Brooks/Cole - Thomson Lewis Acid/Base Reaction

62. 62 © 2006 Brooks/Cole - Thomson Other good examples involve metal ions. Lewis Acids & Bases

63. 63 © 2006 Brooks/Cole - Thomson The combination of metal ions (Lewis acids) with Lewis bases such as H 2 O and NH 3 ------> COMPLEX IONS ------> COMPLEX IONS Lewis Acids & Bases

64. 64 © 2006 Brooks/Cole - Thomson The Lewis Acid-Base Chemistry of Nickel(II)

65. 65 © 2006 Brooks/Cole - Thomson Lewis Acid-Base Interactions in Biology The heme group in hemoglobin can interact with O 2 and CO. The Fe ion in hemoglobin is a Lewis acid O 2 and CO can act as Lewis bases Heme group

66. 66 © 2006 Brooks/Cole - Thomson Many complex ions containing water undergo HYDROLYSIS to give acidic solutions. [Cu(H 2 O) 4 ] 2+ + H 2 O ---> [Cu(H 2 O) 3 (OH)] + + H 3 O + Lewis Acids & Bases

67. 67 © 2006 Brooks/Cole - Thomson This explains why water solutions of Fe 3+, Al 3+, Cu 2+, Pb 2+, etc. are acidic. Lewis Acids & Bases This interaction weakens this bond Another H 2 O pulls this H away as H +

68. 68 © 2006 Brooks/Cole - Thomson AMPHOTERIC nature of some metal hydroxides Al(OH) 3 (s) + 3 H + --> Al 3+ + 3 H 2 O Here Al(OH) 3 is a Brønsted base. Al(OH) 3 (s) + OH - --> Al(OH) 4 - Here Al(OH) 3 is a Lewis acid. Lewis Acids & Bases

69. 69 © 2006 Brooks/Cole - Thomson Formation of complex ions explains why you can dissolve a ppt. by forming a complex ion. AgCl(s)   Ag + + Cl - K sp = 1.8 x 10 -10 Ag + + 2 NH 3 --> Ag(NH 3 ) 2 + K form = 1.6 x 10 7 ------------------------------------- AgCl(s) + 2 NH 3   Ag(NH 3 ) 2 + + Cl - K net = __________________ K net = __________________ Lewis Acids & Bases

70. 70 © 2006 Brooks/Cole - Thomson Why? Why are some compounds acids?Why are some compounds acids? Why are some compounds bases?Why are some compounds bases? Why do acids and bases vary in strength?Why do acids and bases vary in strength? Can we predict variations in acidity or basicity?Can we predict variations in acidity or basicity?

71. 71 © 2006 Brooks/Cole - Thomson Why is CH 3 CO 2 H an Acid? 1. The electronegativity of the O atoms causes the H attached to O to be highly positive. 2. The O—H bond is highly polar. 3. The H atom of O—H is readily attracted to polar H 2 O. Figure 17.9

72. 72 © 2006 Brooks/Cole - Thomson Trichloroacetic acid is a much stronger acid owing to the high electronegativity of Cl.Trichloroacetic acid is a much stronger acid owing to the high electronegativity of Cl. Cl withdraws electrons from the rest of the molecule.Cl withdraws electrons from the rest of the molecule. This makes the O—H bond highly polar. The H of O—H is very positive.This makes the O—H bond highly polar. The H of O—H is very positive. Acetic acid Trichloroacetic acid K a = 1.8 x 10 -5 K a = 0.3

73. 73 © 2006 Brooks/Cole - Thomson These ions are BASES. They become more and more basic as the negative charge increases. As the charge goes up, they interact more strongly with polar water molecules. NO 3 - CO 3 2- Basicity of Oxoanions PO 4 3-