Acids and Bases

1. Acids and Bases

2. Identifying Acids and Bases contains H+ ions as the cation, with and other element as the anion H2SO4 HI • Acids • Acid (anhydrides) • Bases • Base (anhydrides) • Salts Non-metal oxide P2O5 Contains OH- as the anion Combined with a cation Ca(OH)2 Al2O3 A metal with oxygen Ionic compound Formed from a cation and an anion Metal and non-metal Mg F2 KCl LiBr

3. Acid / Base Chemistry • Hydrogen ion concentration = [H+] • Hydroxide ion concentration = [OH-] • Pure H20 – neutral substance – • ph=7 and [H+]=[OH-] • H2O will self-dissociate • H20 > H+ + OH- • Note: the number of H2O molecules that will self dissociate is very small; only 2 molecules per a billion, therefore [H2O] is unchanged.

4. Acid / Base Chemistry • Kw- is the ion product constant for water • Kw= 1.0 x 10-14M2 Kw= [H+] [OH-] FOR H2O:Kw= [1.0 x 10-7M][1.0 x 10-7M] - there is an indirect relationship between [H+] and [OH-]

5. Acid / Base Chemistry • Calculate [OH-] if [H+] is 1.0 x 10-2M • Kw= [H+] [OH-] • [OH-]= Kw = 1.0 x 10-14M2 • [H+] 1.0 x 10-2M • [OH-]= 1.0 X 10 –12M

6. Acid / Base Chemistry • Calculate [H+] if [OH-] is 6.5 x 10-11M • Kw= [H+] [OH-] • [H+]= Kw = 1.0 x 10-14M2 [OH-] 6.5 x 10-11M • [H+]= • [H+] will tell us if a soln is acidic or basic.

7. pH= 1- 6 [H+]= 1.0 x 10 M – 1.0 x 10 M [H+] > [OH-] Acidic solutions -1 -6 pH= 7 [H+] = [OH-] 1.0 x 10 M for both Neutral solutions -7 pH= 8 -14 [H+]= 1.0 x 10 M – 1.0 x 10 M [H+] < [OH-] Basic solutions -8 -14

9. Acid / Base Chemistry • If [H+]= 1.0 x 10-9M, will the solution be basic or acidic? • Basic • Why? • because the pH= 9 and this solution contains less [H+] than [OH-]

10. Acid / Base Chemistry • If [OH-]= 2.63 x 10-4M, will the solution be basic or acidic or neutral? • Why?

11. Acid / Base Formulas • pH= -log [H+] • pOH= -log [OH-] • pH + pOH =14 • [H+] = antilog (-pH) • [OH-] = antilog (-pOH) • How to use the calculator!! • Calculate the pH of a solution with [H+] = 0.001 M. Is this acidic, basic, or neutral?

12. Acid / Base Formulas • Calculate the pH of a solution with [OH-] = 7.9 x 10-3 M. Is this acidic, basic, or neutral? • Calculate the pH of a solution with [H+] = 4.2 x 10-6 M. Acidic, basic, or neutral? What is the [OH-]?

13. Acid / Base Formulas • A solution with a pH of 9.1 has what [H+]? • 2nd log –9.1 ENTER • What is the [OH-]? • What is the pOH?

14. Scientists Who Define Acids / Bases • Arrhenius: Acids: Any substance which releases H+ ion in water solution. Bases: Any substance which releases OH- ion in water solution.

15. Scientists Who Define Acids / Bases • Bronsted - Lowry: Acids: Any substance which donates a proton. Bases: Any substance which accepts a proton.

16. Acids, Bases, and Their Conjugates • Water is amphoteric – has basic + acidic properties. • Conjugate Acid: Substances formed in a reaction when a base gains a H+ • Conjugate Base: Substances formed in a reaction when an acid donates H+

17. Acids, Bases, and Their Conjugates • NH3 + H2O -- NH4+ + OH- • HCl + H2O --->

18. Acids, Bases, and Their Conjugates • CO3-2 + H2O ---> HCO3- + OH- • Ca(OH)2 + 2HNO3 --> Ca(NO3)2 + 2HOH

19. Identifying monoprotic, diprotic, and triprotic: monoprotic: HCl H+ + Cl- diprotic: H2SO4 H+ + HSO4-1 HSO4-1 H+ + SO4-2 triprotic: H3PO4 H+ + H2PO4-1 H2PO4-1 H+ + HPO4-2 HPO4-2 H+ + PO4-3

20. Strengths of Acids and Bases • Strong acids and bases will completely dissociate ex. HCl --> H+ + Cl- • The six strong acids - HCl, HBr, • HI, H2SO4, HNO3, HClO4 • All others are weak. • Strong Bases: Groups I • and II with OH- except Be

21. Strengths of Acids and Bases • Weak acids and bases slightly dissociate ex. HClO <--> ClO- + H+

22. Electrolytes and Non-Electrolytes • Strong Electrolytes: - Compounds that conduct electricity in aqueous solution - Substances that completely dissociate - Strong acids and bases - Soluble salts

23. Electrolytes and Non-Electrolytes • Weak Electrolytes: - Slight electron conductivity - Slight dissociation in aqueous - Weak acids and bases - Insoluble salts if in molten state

24. Electrolytes and Non-Electrolytes • NonElectrolytes: - Don’t conduct electricity - No ions to carry current - Organic, molecular

25. Examples of Electrolytes and Nonelectrolytes: • H2S03 • weak acid/weak elect. • CsOH • strong base/strong elect. • HCl04 • strong acid/strong elect. • C6H1206 • nonelectrolyte- covalent, molecular, organic b/c carbon

26. Examples of Electrolytes and Nonelectrolytes: • Al(OH)3 • weak base/weak electrolyte • HF • weak acid/weak electrolyte • CCl4 • nonelectrolyte- molecular compound • NaN03 • soluble salt/strong electrolyte • S03 • acid anhydride/weak electrolyte

27. Neutralization Reactions: General Equation: • Acid + BaseSalt + Water • HCl + NaOHNaCl + HOH Acid Base Salt Water

28. Neutralization Reactions: Titration:Analytical method used to determine the concentration of acids and bases in a neutralization reaction.

29. Measured volume of an acid or base with unknown concentration. Put in Erlenmeyer. • Add a few drops of indicator to the Ernlenmeyer. • A measured volume of titrant is delivered into the flask through a buret (base or acid) • Concentration of the titrant is known –Standard Solution. • Neutralization occurs when indicator is revealed  End Point • Equivalence Point • MOL ACID = MOL BASE

30. Titration Curve

31. Neutralization practice problems: • What volume of calcium hydroxide in a 3.0 M solution is needed to neutralize 45.0 mL of 2.6 M perchloric acid?

32. Neutralization practice problems: 2. Determine the [Ba(OH)2] solution if 300.0 mL was titrated to neutrality with 220.5 mL of 6.0 M solution of phosphoric acid?

33. Neutralization practice problems: • What volume of calcium hydroxide in a 3.0 M solution is needed to neutralize 45.0 mL of 2.6 M perchloric acid? • G: 45 mL • 2.6 M HCl04 • 3.0 M Ca(OH)2 • U: ? vol Ca(OH)2 M CR M vol mol mol vol Ca(OH)2 + HCl04 2 HOH + Ca(Cl04)2 0.45 L HCl04 x 2.6 mol HCl04 x 1 mol Ca(OH)2 x 1 L Ca(OH)2 1 L Ca(OH)2 2 mol HCl04 3 mol Ca(OH)2 2. Determine the [Ba(OH)2] solution if 300.0 mL was titrated to neutrality with 220.5 mL of 6.0 M solution of phosphoric acid G: 220.5 mL 6.0 M H3P04 300.0 mL Ba(OH)2 U: ? M Ba(OH)2 M CR vol mol mol 3Ba(OH)2 + 2H3P04 Ba3(P04)2 + 6HOH 0.2205 L H3P04 x 6.0 mol H3P04 x 3 mol Ba(OH)2 1 L H3P04 2 mol H3P04 = 1.985 mol Ba(OH)2 1.985 mol Ba(OH)2 0.300L Ba(OH)2 = 6.62 M Ba(OH)2

35. Dissociation examples

36. Acid/Base Chemistry • Hydrogen ion concentration= [H+] • Hydroxide ion concentration= [OH-] • Pure HOH= neutral substance. • Kw is constant for water. [Kw= 1E-14 M2]

37. More Acid/Base Chemistry • Kw = [1x10-7 M][1x10-7 M] (Kw=[H+][OH-]) • Most other substances are not neutral • Indirect relationships between [H+] and [OH-] • [H+] will tell us if solution is Acidic or basic.

38. Strengths of Acids and Bases • Strong Acids: HCl, HI, HBr, H2SO4, HNO3, HClO4 • Strong Bases: Groups I and II with OH- except Be

39. Identifying Electrolytes and Nonelectrolytes: • Strong Electrolytes: • compounds that conduct electricity in aqueous solutions • substance that completely dissociate • strong acids and bases • soluble salts • Weak Electrolytes: • -slight electrical conduct • -slight dissociation in aqueous solution • -conducts in molten state • -weak acids and bases • -insoluble salts (if in molten state) • Nonelectrolytes: • -don’t conduct electricity • -no ions to carry current • -organic, molecular

40. Neutralization • Acid + Base > Salt + H2O • Neutralization is found using titration • Titration: Analytical method used to determine the concentration of acids, bases in a neutralization reaction.

41. Neutralization reactions • Products always end in a salt and water. • Acid + Base = Salt + HOH • Titration- Analytical method used to determin the concentration of acids in a neutralization reaction.

42. Theory