1. Chapter 4.6-4.10 Types of Chemical Reactions and Solution Stoichiometry PHall AP info. NOT integrated into this presentation

2. Chapter 4 Table of Contents Copyright © Cengage Learning. All rights reserved 2 4.6Describing Reactions in Soluti4.6Describing Reactions in Solution 4.7Stoichiometry of Precipitation Reaction4.7Stoichiometry of Precipitation Reactions 4.8Acid–Base Reaction4.8Acid–Base Reactions 4.9Oxidation–Reduction Reaction4.9Oxidation–Reduction Reactions 4.10Balancing Oxidation–Reduction Equation4.10Balancing Oxidation–Reduction Equations

3. Section 4.6 Describing Reactions in Solution Return to TOC Copyright © Cengage Learning. All rights reserved 25 Gives the overall reaction stoichiometry but not necessarily the actual forms of the reactants and products in solution. Reactants and products generally shown as compounds. Use solubility rules to determine which compounds are aqueous and which compounds are solids. AgNO 3 (aq) + NaCl(aq) → AgCl(s) + NaNO 3 (aq) Formula Equation (Molecular Equation)

4. Section 4.6 Describing Reactions in Solution Return to TOC Copyright © Cengage Learning. All rights reserved 26 Represents as ions all reactants and products that are strong electrolytes. Ag + (aq) + NO 3 − (aq) + Na + (aq) + Cl − (aq) → AgCl(s) + Na + (aq) + NO 3 − (aq) Complete Ionic Equation

5. Section 4.6 Describing Reactions in Solution Return to TOC Copyright © Cengage Learning. All rights reserved 27 Includes only those solution components undergoing a change.  Show only components that actually react. Ag + (aq) + Cl − (aq) → AgCl(s) Spectator ions are not included (ions that do not participate directly in the reaction).  Na + and NO 3 − are spectator ions. Net Ionic Equation

6. Section 4.6 Describing Reactions in Solution Return to TOC Copyright © Cengage Learning. All rights reserved 28 Concept Check Write the correct formula equation, complete ionic equation, and net ionic equation for the reaction between cobalt(II) chloride and sodium hydroxide. Formula Equation: CoCl 2 (aq) + 2NaOH(aq) → Co(OH) 2 (s) + 2NaCl(aq) Complete Ionic Equation: Co 2+ (aq) + 2Cl − (aq) + 2Na + (aq) + 2OH − (aq) → Co(OH) 2 (s) + 2Na + (aq) + 2Cl − (aq) Net Ionic Equation: Co 2+ (aq) + 2Cl − (aq) → Co(OH) 2 (s)

7. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 29 1. Identify the species present in the combined solution, and determine what reaction if any occurs. 2. Write the balanced net ionic equation for the reaction. 3. Calculate the moles of reactants. 4. Determine which reactant is limiting. 5. Calculate the moles of product(s), as required. 6. Convert to grams or other units, as required. Solving Stoichiometry Problems for Reactions in Solution

8. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 30 Concept Check (Part I) 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change).  What precipitate will form? lead(II) phosphate, Pb 3 (PO 4 ) 2  What mass of precipitate will form? 1.1 g Pb 3 (PO 4 ) 2

9. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 31 Where are we going?  To find the mass of solid Pb 3 (PO 4 ) 2 formed. How do we get there?  What are the ions present in the combined solution?  What is the balanced net ionic equation for the reaction?  What are the moles of reactants present in the solution?  Which reactant is limiting?  What moles of Pb 3 (PO 4 ) 2 will be formed?  What mass of Pb 3 (PO 4 ) 2 will be formed? Let’s Think About It

10. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 32 Concept Check (Part II) 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change).  What is the concentration of nitrate ions left in solution after the reaction is complete? 0.27 M

11. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 33 Where are we going?  To find the concentration of nitrate ions left in solution after the reaction is complete. How do we get there?  What are the moles of nitrate ions present in the combined solution?  What is the total volume of the combined solution? Let’s Think About It

12. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 34 Concept Check (Part III) 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change).  What is the concentration of phosphate ions left in solution after the reaction is complete? 0.011 M

13. Section 4.7 Stoichiometry of Precipitation Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 35 Where are we going?  To find the concentration of phosphate ions left in solution after the reaction is complete. How do we get there?  What are the moles of phosphate ions present in the solution at the start of the reaction?  How many moles of phosphate ions were used up in the reaction to make the solid Pb 3 (PO 4 ) 2 ?  How many moles of phosphate ions are left over after the reaction is complete?  What is the total volume of the combined solution? Let’s Think About It

14. ACIDS AND BASES www.lab-initio.com

15. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 36 Acid—proton donor Base—proton acceptor For a strong acid and base reaction: H + (aq) + OH – (aq) →  H 2 O(l) Acid–Base Reactions (Brønsted–Lowry)

16. Properties of Acids  Acids are proton (hydrogen ion, H + ) donors  Acids have a pH lower than 7  Acids taste sour  Acids effect indicators  Blue litmus turns red  Methyl orange turns red  Acids react with active metals, producing H 2  Acids react with carbonates  Acids neutralize bases

17. Acids are Proton (H + ion) Donors Strong acids are assumed to be 100% ionized in solution (good H + donors). Weak acids are usually less than 5% ionized in solution (poor H + donors). HClH 2 SO 4 HNO 3 H 3 PO 4 HC2H3O2HC2H3O2 Organic acids

18. Acids Have a pH less than 7

19. Acids Effect Indicators Blue litmus paper turns red in contact with an acid. Methyl orange turns red with addition of an acid

20. Acids React with Active Metals Acids react with active metals to form salts and hydrogen gas. Mg + 2HCl  MgCl 2 + H 2 (g) Zn + 2HCl  ZnCl 2 + H 2 (g) Mg + H 2 SO 4  MgSO 4 + H 2 (g)

21. Acids React with Carbonates 2HC 2 H 3 O 2 + Na 2 CO 3 2 NaC 2 H 3 O 2 + H 2 O + CO 2

22. Effects of Acid Rain on Marble (calcium carbonate) George Washington: BEFORE George Washington: AFTER

23. Acids Neutralize Bases HCl + NaOH  NaCl + H 2 O Neutralization reactions ALWAYS produce a salt and water. H 2 SO 4 + 2NaOH  Na 2 SO 4 + 2H 2 O 2HNO 3 + Mg(OH) 2  Mg(NO 3 ) 2 + 2H 2 O

24. Properties of Bases  Bases are proton (hydrogen ion, H + ) acceptors  Bases have a pH greater than 7  Bases taste bitter  Bases effect indicators  Red litmus turns blue  Phenolphthalein turns purple  Solutions of bases feel slippery  Bases neutralize acids

25. Bases are Proton (H + ion) Acceptors  Sodium hydroxide (lye), NaOH  Potassium hydroxide, KOH  Magnesium hydroxide, Mg(OH) 2  Calcium hydroxide (lime), Ca(OH) 2 OH - (hydroxide) in base combines with H + in acids to form water H + + OH -  H 2 O

26. Bases have a pH greater than 7

27. Bases Effect Indicators Red litmus paper turns blue in contact with a base. Phenolphthalein turns bright pink in a base.

28. Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH) 2, which neutralizes stomach acid, HCl. 2 HCl + Mg(OH) 2 MgCl 2 + 2 H 2 O

29. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 37 Neutralization of a Strong Acid by a Strong Base

30. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 38 1. List the species present in the combined solution before any reaction occurs, and decide what reaction will occur. 2. Write the balanced net ionic equation for this reaction. 3. Calculate moles of reactants. 4. Determine the limiting reactant, where appropriate. 5. Calculate the moles of the required reactant or product. 6. Convert to grams or volume (of solution), as required. Performing Calculations for Acid – Base Reactions

31. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 39 Titration – delivery of a measured volume of a solution of known concentration (the titrant) into a solution containing the substance being analyzed (the analyte). Equivalence point – enough titrant added to react exactly with the analyte. Endpoint – the indicator changes color so you can tell the equivalence point has been reached. Acid–Base Titrations

32. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 40 Concept Check For the titration of sulfuric acid (H 2 SO 4 ) with sodium hydroxide (NaOH), how many moles of sodium hydroxide would be required to react with 1.00 L of 0.500 M sulfuric acid to reach the endpoint? 1.00 mol NaOH

33. Section 4.8 Acid–Base Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 41 Where are we going?  To find the moles of NaOH required for the reaction. How do we get there?  What are the ions present in the combined solution? What is the reaction?  What is the balanced net ionic equation for the reaction?  What are the moles of H + present in the solution?  How much OH – is required to react with all of the H + present? Let’s Think About It

34. Acid-Base Reactions

35. Copyright © Houghton Mifflin Company. All rights reserved.4– Proton Transfer Click here to watch visualization

36. Copyright © Houghton Mifflin Company. All rights reserved.4– Neutralization of a Strong Acid by a Strong Base Click here to watch visualization.

37. Copyright © Houghton Mifflin Company. All rights reserved.4– Acid-Base Titration Click here to watch video.

38. Copyright © Houghton Mifflin Company. All rights reserved.4– Key Titration Terms Titrant - solution of known concentration used in titration. Analyte - substance being analyzed. Equivalence point - enough titrant added to react exactly with the analyte. Endpoint - the indicator changes color so you can tell the equivalence point has been reached.

39. Copyright © Houghton Mifflin Company. All rights reserved.4– Performing Calculations for Acid-Base Reactions 1. List initial species and predict reaction. 2. Write balanced net ionic reaction. 3. Calculate moles of reactants. 4. Determine limiting reactant. 5. Calculate moles of required reactant or product. 6. Convert to grams or volume, as required.

40. Oxidation-Reduction Reactions “Redox” LEO SAYS GER Lose Electrons = Oxidation Gain Electrons = Reduction OIL RIG Oxidation is Loss of Electrons Reduction is Gain of Electrons

41. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 42 Reactions in which one or more electrons are transferred. Redox Reactions

42. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 43 Reaction of Sodium and Chlorine

43. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 44 1. Oxidation state of an atom in an element = 0 2. Oxidation state of monatomic ion = charge of the ion 3. Oxygen = −2 in covalent compounds (except in peroxides where it = −1) 4. Hydrogen = +1 in covalent compounds 5. Fluorine = −1 in compounds 6. Sum of oxidation states = 0 in compounds 7. Sum of oxidation states = charge of the ion in ions Rules for Assigning Oxidation States

44. Copyright © Houghton Mifflin Company. All rights reserved.4– Table 4.2 Rules for Assigning Oxidation States

45. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 45 Exercise Find the oxidation states for each of the elements in each of the following compounds: K 2 Cr 2 O 7 CO 3 2- MnO 2 PCl 5 SF 4 K = +1; Cr = +6; O = –2 C = +4; O = –2 Mn = +4; O = –2 P = +5; Cl = –1 S = +4; F = –1

46. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 46 Transfer of electrons Transfer may occur to form ions Oxidation – increase in oxidation state (loss of electrons); reducing agent Reduction – decrease in oxidation state (gain of electrons); oxidizing agent Redox Characteristics

47. Section 4.9 Oxidation–Reduction Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 47 Concept Check Which of the following are oxidation-reduction reactions? Identify the oxidizing agent and the reducing agent. a) Zn(s) + 2HCl(aq) → ZnCl 2 (aq) + H 2 (g) b) Cr 2 O 7 2- (aq) + 2OH - (aq) → 2CrO 4 2- (aq) + H 2 O(l) c) 2CuCl(aq) → CuCl 2 (aq) + Cu(s)

48. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 48 1. Write the unbalanced equation. 2. Determine the oxidation states of all atoms in the reactants and products. 3. Show electrons gained and lost using “tie lines.” 4. Use coefficients to equalize the electrons gained and lost. 5. Balance the rest of the equation by inspection. 6. Add appropriate states. Balancing Oxidation–Reduction Reactions by Oxidation States

49. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 49 Balance the reaction between solid zinc and aqueous hydrochloric acid to produce aqueous zinc(II) chloride and hydrogen gas.

50. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 50 Zn(s) + HCl(aq) → Zn 2+ (aq) + Cl – (aq) + H 2 (g) 1. What is the unbalanced equation?

51. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 51 Zn(s) + HCl(aq) → Zn 2+ (aq) + Cl – (aq) + H 2 (g) 0 +1 –1 +2 –1 0 2. What are the oxidation states for each atom?

52. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 52 1 e – gained (each atom) Zn(s) + HCl(aq) → Zn 2+ (aq) + Cl – (aq) + H 2 (g) 0 +1 –1 +2 –1 0 2 e – lost The oxidation state of chlorine remains unchanged. 3. How are electrons gained and lost?

53. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 53 1 e – gained (each atom) × 2 Zn(s) + HCl(aq) → Zn 2+ (aq) + Cl – (aq) + H 2 (g) 0 +1 –1 +2 –1 0 2 e – lost Zn(s) + 2HCl(aq) → Zn 2+ (aq) + Cl – (aq) + H 2 (g) 4. What coefficients are needed to equalize the electrons gained and lost?

54. Section 4.10 Balancing Oxidation–Reduction Equations Return to TOC Copyright © Cengage Learning. All rights reserved 54 Zn(s) + 2HCl(aq) → Zn 2+ (aq) + 2Cl – (aq) + H 2 (g) 5. What coefficients are needed to balance the remaining elements?

55. Oxidation and Reduction (Redox)  Electrons are transferred  Spontaneous redox rxns can transfer energy  Electrons (electricity)  Heat  Non-spontaneous redox rxns can be made to happen with electricity

56. Oxidation Reduction Reactions (Redox) Each sodium atom loses one electron: Each chlorine atom gains one electron: → → → PLEASE NOTE THAT THE circle R should be a reaction arrow and the R should NOT be here. This came from a different presentation and will not let me edit or delete the R as it was made with a PPT and converted to the MAC version. I tried to add arrows to show that this should be in it’s place by putting it on or near the R.

57. LEO says GER : LEO says GER : Lose Electrons = Oxidation Sodium is oxidized Gain Electrons = Reduction Chlorine is reduced OIL RIG Oxidation is Loss of Electrons Reduction is Gain of Electrons → →

58. Not All Reactions are Redox Reactions Reactions in which there has been no change in oxidation number are not redox rxns. Examples: → →

59. Rules for Assigning Oxidation Numbers Rules 1 & 2 1.The oxidation number of any uncombined element is zero 2. The oxidation number of a monatomic ion equals its charge →

60. Rules for Assigning Oxidation Numbers Rules 3 & 4 3. The oxidation number of oxygen in compounds is -2 4. The oxidation number of hydrogen in compounds is +1

61. Rules for Assigning Oxidation Number Rule 5 5. The sum of the oxidation numbers in the formula of a compound is 0 2(+1) + (-2) = 0 H O (+2) + 2(-2) + 2(+1) = 0 Ca O H

62. Rules for Assigning Oxidation Numbers Rule 6 6. The sum of the oxidation numbers in the formula of a polyatomic ion is equal to its charge X + 3(-2) = -1 N O  X = +5  X = +6 X + 4(-2) = -2 S O

63. The Oxidation Number Rules - SIMPLIFIED 1. The sum of the oxidation numbers in ANYTHING is equal to its charge 2. Hydrogen in compounds is +1 3. Oxygen in compounds is -2

64. Reducing Agents and Oxidizing Agents  The substance reduced is the oxidizing agent  The substance oxidized is the reducing agent Sodium is oxidized – it is the reducing agent Chlorine is reduced – it is the oxidizing agent → →

65. Trends in Oxidation and Reduction Active metals: Lose electrons easily Are easily oxidized Are strong reducing agents Active nonmetals: Gain electrons easily Are easily reduced Are strong oxidizing agents

66. Redox Reaction Prediction #1 Important OxidizersFormed in reaction MnO 4 - (acid solution) MnO 4 - (basic solution) MnO 2 (acid solution) Cr 2 O 7 2- (acid) CrO 4 2- HNO 3, concentrated HNO 3, dilute H 2 SO 4, hot conc Metallic Ions Free Halogens HClO 4 Na 2 O 2 H 2 O 2 Mn(II) MnO 2 Mn(II) Cr(III) NO 2 NO SO 2 Metallous Ions Halide ions Cl - OH - O 2

67. Redox Reaction Prediction #2 Important ReducersFormed in reaction Halide Ions Free Metals Metalous Ions Nitrite Ions Sulfite Ions Free Halogens (dil, basic sol) Free Halogens (conc, basic sol) C 2 O 4 2- Halogens Metal Ions Metallic ions Nitrate Ions SO 4 2- Hypohalite ions Halate ions CO 2

68. END OF Oxidation- Reduction Reactions AND Ch.4