1. Reactions in Aqueous Solution Chapter 4 Dr. Ali Bumajdad

2. Chapter 4 Topics Solution Electrolytes, acids and bases Precipitation reactions and solubility rules Molecular eqn., ionic eqn & net ionic eqn. Oxidation reduction reactions (Redox Reactions) Molarity and Dilution Solution Stoichiometry (gravimetric analysis, titrations, limiting reactant….etc) Solution Stoichiometry Dr. Ali Bumajdad

3. solution is a homogenous mixture of 2 or more substances solute is(are) the substance(s) present in the smaller amount(s) solvent is the substance present in the larger amount SolutionSolventSolute Soft drink (l) Air (g) Soft Solder (s) H2OH2O N2N2 Pb Sugar, CO 2 O 2, Ar, CH 4 Sn Solution Dr. Ali Bumajdad

4. Electrolyte is a substance when dissolved in water results in a solution that can conduct electricity. Nonelectrolyte is a substance when dissolved results in a solution that does not conduct electricity. nonelectrolyte weak electrolyte strong electrolyte Why? Because it gives ion when dissolve in water Why? Because it does not dissociates into ions Electrolytes, acids and bases

5. Strong Electrolyte: 100% dissociation NaCl (s) Na + (aq) + Cl - (aq) H2OH2O Weak Electrolyte: not completely dissociated CH 3 COOH CH 3 COO - (aq) + H + (aq) Dissociation or Ionization ? Cations (+) and Anions (-) HCl (l) H + (aq) + Cl - (aq) H2OH2O NaOH (l) Na + (aq) + OH - (aq) H2OH2O Soluble salt Strong acid Strong Base Weak acid Weak base NH 3 + H 2 O NH 4 + (aq) + OH - (aq) 1% 0.1M1% Dr. Ali Bumajdad

6. Non-electrolyte: No dissociation into ions Example: Sugar, ethanol (CH 3 CH 2 OH) (Note that sugar and ethanol (CH 3 CH 2 OH) soluble in water but do not gives ions when dissolved) Q) Which of the following is not a strong electrolytes: 1) KCl6)H 2 SO 4 11) H 2 O 2)LiOH7)HCl12) HF 3)NaNO 3 8)HNO 3 13)HBr 4)NH 3 9)KOH14) H 3 PO 4 5)Suger10)HC 2 H 3 O 2 C 6 H 12 O 6 (s) C 6 H 12 O 6 (aq) H2OH2O Dr. Ali Bumajdad

7. Acids Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid. React with certain metals to produce hydrogen gas. React with carbonates and bicarbonates to produce carbon dioxide gas 2HCl (aq) + Mg (s) MgCl 2 (aq) + H 2 (g) 2HCl (aq) + CaCO 3 (s) CaCl 2 (aq) + CO 2 (g) + H 2 O (l) Aqueous acid solutions conduct electricity. Dr. Ali Bumajdad

8. Have a bitter taste. Feel slippery. Many soaps contain bases. Bases Aqueous base solutions conduct electricity. Dr. Ali Bumajdad

9. Arrhenius acid is a substance that produces H + (H 3 O + ) in water Arrhenius base is a substance that produces OH - in water Dr. Ali Bumajdad

10. A Brønsted acid is a proton donor A Brønsted base is a proton acceptor acidbaseacidbase A Brønsted acid must contain at least one ionizable proton! Dr. Ali Bumajdad

11. Monoprotic acids HCl H + + Cl - HNO 3 H + + NO 3 - CH 3 COOH H + + CH 3 COO - Strong electrolyte, strong acid Weak electrolyte, weak acid Diprotic acids H 2 SO 4 H + + HSO 4 - HSO 4 - H + + SO 4 2- Strong electrolyte, strong acid Weak electrolyte, weak acid Triprotic acids H 3 PO 4 H + + H 2 PO 4 - H 2 PO 4 - H + + HPO 4 2- HPO 4 2- H + + PO 4 3- Weak electrolyte, weak acid Dr. Ali Bumajdad

12. Q) Identify each of the following species as a Brønsted acid, base, or both. (a) HI, (b) CH 3 COO -, (c) H 2 PO 4 - HI (aq) H + (aq) + I - (aq)Brønsted acid CH 3 COO - (aq) + H + (aq) CH 3 COOH (aq)Brønsted base H 2 PO 4 - (aq) H + (aq) + HPO 4 2- (aq) H 2 PO 4 - (aq) + H + (aq) H 3 PO 4 (aq) Brønsted acid Brønsted base Dr. Ali Bumajdad

14. Acid- Base Equilibria 1) Arrhenius Definition:  Acid: Substance when dissolved in water increase H +  Base:Substance when dissolved in water increase OH - 2) BrØnsted-Lowry Definition:  Acid: Substance that donateH +  Base:Substance that accept H + 3) Lewis Definition:  Acid: Electron-pair acceptor  Base:Electron pair donor

15. Neutralization Reaction acid + base salt + water HCl (aq) + NaOH (aq) NaCl (aq) + H 2 O H + + Cl - + Na + + OH - Na + + Cl - + H 2 O H + + OH - H 2 O Dr. Ali Bumajdad

16.  A weak acid is a weak electrolyte A strong acid is a strong electrolyte A weak base is a weak electrolyte A strong base is a strong electrolyte Dr. Ali Bumajdad

17. Hydration the process in which an ion is surrounded by water molecules   H2OH2O Dr. Ali Bumajdad

19. Precipitate: insoluble solid that separates from solution PbI 2 Dr. Ali Bumajdad Precipitation reactions and solubility rules

20. Solubility Rules soluble salts Soluble salts with exceptions insoluble salts with exceptions cation salts 1) alkali metals salts e.g. NaCl 2) ammonium ion salts e.g. (NH 4 ) 2 SO 4 Anions salts 1) nitrate ion salts e.g. KNO 3 2) chlorate ion salts e.g. NaClO 3 3) perchlorate ion salts e.g. KClO 4 4) acetate ion salts e.g. Cu(C 2 H 3 O 2 ) 2 All chlorides, bromides, Iodides except those of Ag +, Pb 2+ and Hg 2 2+ e.g. MgI 2 All sulfates (SO 4 2- ) except those of Ag +, Ca 2+, Sr 2+, Ba 2+ Pb 2+, and Hg 2+ e.g. MgSO 4 All metals oxides except those of alkali metals, Ca 2+, Sr 2+, Ba 2+ e.g. MgO All hydroxides except those of alkali metals, Ca 2+, Sr 2+, Ba 2+ e.g. Be(OH) 2 All carbonates (CO 3 2- ), phosphates ( PO 4 3- ), sulfides (S 2- ) and sulfites (SO 3 2- ), and chromate (CrO 4 2- ) except those of NH 4 +, alkali metals e.g. CaCO 3 Dr. Ali Bumajdad

22. Q) Soluble or not: a) Na 2 S g) Ni(OH) 2 c) AgBr e) Cu(C 2 H 3 O 2 ) 2 f) PbSO 4 d) ZnO b) FeCO 3 Soluble Not Soluble Soluble Not Soluble Dr. Ali Bumajdad

24. Writing Net Ionic Equations 1.Write the balanced molecular equation. 2.Write the ionic equation showing the strong electrolytes completely dissociated into cations and anions. 3.Cancel the spectator ions on both sides of the ionic equation AgNO 3 (aq) + NaCl (aq) AgCl (s) + NaNO 3 (aq) Ag + + NO 3 - + Na + + Cl - AgCl (s) + Na + + NO 3 - Ag + + Cl - AgCl (s) Q) Write the net ionic equation for the reaction of silver nitrate with sodium chloride. Dr. Ali Bumajdad Molecular eqn., ionic eqn & net ionic eqn.

25. molecular equation ionic equation net ionic equation Pb 2+ + 2NO 3 - + 2Na + + 2I - PbI 2 (s) + 2Na + + 2NO 3 - Na + and NO 3 - are spectator ions Pb(NO 3 ) 2 (aq) + 2NaI (aq) PbI 2 (s) + 2NaNO 3 (aq) precipitate Pb 2+ + 2I - PbI 2 (s) PbI 2 Dr. Ali Bumajdad

26. Sa. Ex. 4.8: what happen when the following pairs mixed: a) KNO 3 and BaCl 2 b) Na 2 SO 4 and Pb(NO 3 ) 2 c) KOH and Fe(NO 3 ) 3 No net ionic eqn. No reaction reaction 2KNO 3 (aq) + BaCl 2 (aq) Ba(NO 3 ) 2 (aq) + 2KCl (aq) Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) 2NaNO 3 (aq) + PbSO 4 (s) 3KOH (aq) + Fe(NO 3 ) 3 (aq) 3KNO 3 (aq) + Fe(OH) 3 (s) Dr. Ali Bumajdad

27. Sa. Ex. 4.9: Write the molecular, complete ionic and net ionic equations for the following mixed chemicals: 1) Potassium Chloride added to silver nitrate 2) Potassium hydroxide added to iron (III) nitrate Dr. Ali Bumajdad

28. Q) Write the molecular, complete ionic and net ionic equations for the following mixed chemicals: K 2 CrO 4 and Ba(NO 3 ) 2 HCl and NaOH HC 2 H 3 O 2 and KOH Dr. Ali Bumajdad

30. Oxidation-Reduction Reactions (electron transfer reactions) 2Mg (s) + O 2 (g) 2MgO (s) 2Mg 2Mg 2+ + 4e - Oxidation half-reaction (lose e - ) Redox Reactions Oxidation: Loss of electrons neutral Cation We can say : Oxidation of Mg or Mg is oxidized We can say : Mg is a reducing agent

31. Reduction: Gain of electrons O 2 + 4e - 2O 2- Reduction half-reaction (gain e - ) 2Mg + O 2 + 4e - 2Mg 2+ + 2O 2- + 4e - 2Mg + O 2 2MgO Redox reaction: Gaining and losing of electrons neutralanion Dr. Ali Bumajdad We can say : reduction of O 2 or O 2 is reduced We can say : O 2 is oxidation agent

32. Oxidizing agent: Reactant that gain electrons Reducing agent: Reactant that lost electrons Oxidizing agent: Reactant reduced Reducing agent: Reactant oxidized Dr. Ali Bumajdad

34. Oxidation number The charge the atom would have in a molecule (or an ionic compound) if electrons were completely transferred. 1. O.N. of free elements is zero. Na, Be, K, Pb, H 2, O 2, P 4 = 0 2. O.N. of monatomic ions = the charge on the ion. Li +, Li = +1; Fe 3+, Fe = +3; O 2-, O = -2 3. The sum of O.N. in a molecule is Zero Dr. Ali Bumajdad H 2 O = 2(+1) +(-2) =0 4. The sum of O.N. in a polyatomic ion = the charge on ion. SO 4 -2 = (X) +4(-2) =-2 5. Group IA metals = +1, IIA metals = +2

35. 6. F O.N. = -1. 7. H O.N. = +1, except with metals in binary compounds = –1. 8. O O.N. = -2, except in H 2 O 2 and O 2 2- = –1. 9. When encounter conflict in rules 6, 7, 8 the higher one take precedence. Dr. Ali Bumajdad

36. Figure 4.10 The oxidation numbers of elements in their compounds

37. Zn (s) + CuSO 4 (aq) ZnSO 4 (aq) + Cu (s) Zn is oxidizedZn Zn 2+ + 2e - Cu 2+ is reducedCu 2+ + 2e - Cu Zn is the reducing agent Cu 2+ is the oxidizing agent Q) Copper wire reacts with silver nitrate to form silver metal. What is the oxidizing agent in the reaction? Cu (s) + 2AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2Ag (s) Cu Cu 2+ + 2e - Ag + + 1e - AgAg + is reducedAg + is the oxidizing agent Cu is oxidizedCu is the reducing agent Dr. Ali Bumajdad Q) Zinc reacts with copper sulfate to form copper metal. What is the reducing agent in the reaction?

38. NaIO 3 Na = +1 O = -2 3x(-2) + 1 + ? = 0 I = +5 IF 7 F = -1 7x(-1) + I (?) = 0 I = +7 K 2 Cr 2 O 7 O = -2K = +1 7x(-2) + 2x(+1) + 2x(Cr(?) = 0 Cr = +6 Q) What are the oxidation numbers of all the elements in the following ? HCO 3 - O = -2H = +1 3x(-2) + 1 + ? = -1 C = +4

39. Sa. Ex. 4.16: Assign oxidation states of all the atoms in: a)CO 2 b)SF 6 c)NO 3 - Dr. Ali Bumajdad

40. Q) Assign oxidation states of all the atoms in: a)FeCl 3 b) KNO 3 c) H 2 O 2 d) Fe 2 (SO 4 ) 3 e) Cr 2 O 7 f) ClO 3 - g) Na 2 S 4 O 6

42. Types of Oxidation-Reduction Reactions Combination Reaction A + B C S + O 2 SO 2 Decomposition Reaction 2KClO 3 2KCl + 3O 2 C A + B 00 +4-2 +1+5-2+10

43. Displacement Reaction A + BC AC + B Sr + 2H 2 O Sr(OH) 2 + H 2 TiCl 4 + 2Mg Ti + 2MgCl 2 Cl 2 + 2KBr 2KCl + Br 2 Hydrogen Displacement Metal Displacement Halogen Displacement Types of Oxidation-Reduction Reactions 0 +1+20 0+40+2 0 0 Dr. Ali Bumajdad

44. The Activity Series for Metals M + BC AC + B Hydrogen Displacement Reaction M is metal BC is acid or H 2 O B is H 2 Ca + 2H 2 O Ca(OH) 2 + H 2 Pb + 2H 2 O Pb(OH) 2 + H 2 Dr. Ali Bumajdad

45. Disproportionation Reaction Cl 2 + 2OH - ClO - + Cl - + H 2 O Element is simultaneously oxidized and reduced. Types of Oxidation-Reduction Reactions Chlorine Chemistry 0 +1 Dr. Ali Bumajdad

46. Ca 2+ + CO 3 2- CaCO 3 NH 3 + H + NH 4 + Zn + 2HCl ZnCl 2 + H 2 Ca + F 2 CaF 2 Precipitation, Combination Acid-Base, Combination Redox (H 2 Displacement) Redox, Combination Q) Classify the following reactions. Dr. Ali Bumajdad

48. Chemistry in Action: Breath Analyzer +6 +3 Dr. Ali Bumajdad 3CH 3 CH 2 OH + 2K 2 Cr 2 O 7 + 8H 2 SO 4 Orange/ yellow 3CH 3 COOH + 2Cr 2 (SO 4 ) 3 + 2K 2 SO 4 + 11H 2 O green

49. Sa. Ex. 4.17: 2Al(s) + 3 I 2 (s) 2Al I 3 (s) Identify the atoms that are oxidized, reduced and specify the oxidation and reducing agent. Dr. Ali Bumajdad

50. Q) 14HCl + K 2 Cr 2 O 7 2KCl + 2CrCl 3 + 3Cl 2 + 7H 2 O Identify the atoms that are oxidized, reduced and specify the oxidation and reducing agent. Dr. Ali Bumajdad

51. Molarity and Dilution Q) What mass of KI is required to make 500. mL of a 2.80 M KI solution? = 232 g KI M = molarity = no. of moles of solute Volume of solution in liters (7) M = n V L solution (7) Dr. Ali Bumajdad

52. Sa. Ex. 4.1: Calculate M for a solution prepared by dissolving 11.5 g of NaOH in enough water to make 1.50 L of solution. =0.192 M Sa. Ex. 4.2: Calculate M for a solution prepared by dissolving 1.56 g of HCl in enough water to make 26.8 ml of solution. =1.60 M Dr. Ali Bumajdad

53. Sa. Ex. 4.3: Give concentration of each type of ions : a)0.50 M Co(NO 3 ) 2 b) 1 M Fe(ClO 4 ) 3 Sa. Ex. 4.4: Calculate number of moles of Cl - in 1.75 L of 1.0×10 -3 M ZnCl 2

54. Sa. Ex. 4.5: Typical blood serum is about 0.14 M NaCl. What volume of blood contains 1.0 mg NaCl =1.2 ×10 -4 L Sa. Ex. 4.6: What is the mass of K 2 Cr 2 O 7 in 1 L of 0.200 M solution =58.8 g Dr. Ali Bumajdad

56. Dilution: solute moles before dilution = solute moles after dilution M before dil V before dil = M after dil V after dil (8) M i V i = M f V f (8) Only for Dilution Dr. Ali Bumajdad Dilution Add Solvent preparing a less concentrated solution from a more concentrated one.

57. Sa. Ex. 4.7: What volume of 16 M H 2 SO 4 must be used to prepare 1.5 L of 0.10 M H 2 SO 4 solution = 9.4 ×10 -3 L = 9.4 ml Dr. Ali Bumajdad

58. Q) How would you prepare 60.0 mL of 0.2 M HNO 3 from a stock solution of 4.00 M HNO 3 ? M i V i = M f V f M i = 4.00 M f = 0.200V f = 0.06 L V i = ? L V i = MfVfMfVf MiMi = 0.200 x 0.06 4.00 = 0.003 L = 3 mL 3 mL of acid + 57 mL of water= 60 mL of solution Dr. Ali Bumajdad

59. V = 102 ml

60. Solution Stoichiometry Dr. Ali Bumajdad Gravimetric analysis 1.Dissolve unknown substance in water 2.React unknown with known substance to form a precipitate 3.Filter and dry precipitate 4.Weigh precipitate 5.Use chemical formula and mass of precipitate to determine amount of unknown ion

62. a solution of accurately known concentration added gradually to another solution of unknown concentration until the chemical reaction between the two solutions is complete Equivalence point : the point at which the reaction is complete Indicator : substance that changes color at (or near) the equivalence point Dr. Ali Bumajdad Titrations n H M aicd V acid = n OH M base V base (9) no. of H in the acid (per formula) no. of OH in the base (per formula)

63. Q) What volume of a 1.420 M NaOH solution is required to titrate 25.00 mL of a 4.50 M H 2 SO 4 solution? WRITE THE CHEMICAL EQUATION! H 2 SO 4 + 2NaOH 2H 2 O + Na 2 SO 4 = 158 mL Dr. Ali Bumajdad n Ox M Ox V Ox = n Red M Red V Red (10) no. of e lost (per formula) no. of e gained (per formula)

64. = 0.1141 M

65. = 16.1 ml

66. n Ox M Ox V Ox = n Red M Red V Red (10) no. of e lost (per formula) no. of e gained (per formula)

67. Sa. Ex. 4.10: what mass of NaCl must be added to 1.50 L of a 0.100 M AgNO 3 solution to precipitate all the Ag + ions in the form of AgCl = 8.77g Dr. Ali Bumajdad

68. Sa. Ex. 4.11: Calculate the mass of PbSO 4 formed when 1.25 L of 0.0500 M Pb(NO 3 ) 2 and 2.00L of 0.0250 M Na 2 SO 4 are mixed. =15.2 g Dr. Ali Bumajdad

69. Sa. Ex. 4.13: 28.0 ml of 0.250 M HNO 3 and 53.0ml of 0.320 M KOH are mixed. Calculate the amount of water formed. What is the concentration of H+ or OH - in excess after the reaction goes to completion. = 0.123 M OH - in excess = 0.00996 mol of water Dr. Ali Bumajdad

70. Sa. Ex. 4.14: 1.3009 g of KHC 8 H 4 O 4 (M.m.=204.22 g/mol) dissolved in water and few drops of PhPh is added. The solution is titrated with NaOH solution. The different between the final and initial burette reading was 41.20 ml. Calculate the concentration of NaOH solution. = 0.1546 M Dr. Ali Bumajdad

71. Sa. Ex. 4.15: Waste materials of CCl 4 + HC 7 H 5 O 2 = 0.3518 g was shaken with water. The resulting aqueous solution required 10.59 ml of 0.1546 M NaOH for neutralization. Calculate the mass % of HC 7 H 5 O 2 in the waste. =56.82% Dr. Ali Bumajdad