1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Table of Contents Chapter 8 Chemical Equations and Reactions Section 1 Describing Chemical Reactions Section 2 Balancing Chemical Equations Section 3 Classifying Chemical Reactions Section 4 Writing Net Ionic Equations

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Describing Chemical Reactions Bellringer For the following situations, list observations that you think indicate that a chemical reaction has taken place: a cut apple turns brown an egg changes when it cooks a log burns a car rusts Chapter 8

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives List evidence that suggests that a chemical reaction has occurred and evidence that proves that a chemical reaction has occurred. Describe a chemical reaction by using a word equation and a formula equation. Interpret notations in formula equations, such as those relating to states of matter or reaction conditions. Section 1 Describing Chemical Reactions Chapter 8

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A chemical reaction is the process by which one or more substances change into one or more new substances. Reactants are the original substances in a chemical reaction. Products are the substances that are created in a chemical reaction. Section 1 Describing Chemical Reactions Chapter 8 Chemical Reaction

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Chemical Reaction Chapter 8

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Evidence of a Chemical Reaction Section 1 Describing Chemical Reactions Chapter 8

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Signs of a Chemical Reaction Chapter 8

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Precipitate Chapter 8

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Evidence of a Chemical Reaction Section 1 Describing Chemical Reactions solution color changes solution bubbles copper is used up Chapter 8

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Reaction Versus Physical Change chemical change – new substance forms with properties that differ from original substance density boiling point melting point physical change - changes of state evaporation condensation melting freezing Section 1 Describing Chemical Reactions Chapter 8

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reactions and Energy Changes Energy can be released in a chemical reaction. methane + oxygen  carbon dioxide + water + energy Energy is a product. Energy can be absorbed in a chemical reaction. dinitrogen tetroxide + energy  nitrogen dioxide Energy is a reactant. Section 1 Describing Chemical Reactions Chapter 8

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Constructing a Chemical Equation A chemical equation shows the chemical formulas and relative amounts of all reactants and products. A word equation contains the names of the reactants and products. Equations must be balanced. Section 1 Describing Chemical Reactions Chapter 8

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Writing a Word Equation or Formula Equation methane + oxygen  carbon dioxide + water ?CH 4 + ?O 2  ?CO 2 + ?H 2 O Section 1 Describing Chemical Reactions Chapter 8

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Equations and Reaction Information Physical States NaHCO 3 (s) + HC 2 H 3 O 2 (aq)  NaC 2 H 3 O 2 (aq) + CO 2 (aq) + H 2 O(l) solid liquid Section 1 Describing Chemical Reactions Chapter 8 catalyst N 2 (g) + 3H 2 (g) 2NH 3 (g) aqueous solutions Reaction Conditions 350°C, 25 000 kPa

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Equations and Reaction Information Section 1 Describing Chemical Reactions Chapter 8

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Chemical Equation Chapter 8

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Balancing Chemical Equations Bellringer Write a word equation for baking a cake. Does the cake have the same properties as the ingredients? Answer: sugar + flour + eggs + vanilla + salt  cake The properties are different. Chapter 8

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Relate the conservation of mass to the rearrangement of atoms in a chemical reaction. Write and interpret a balanced chemical equation for a reaction, and relate conservation of mass to the balanced equation. Section 2 Balancing Chemical Equations Chapter 8

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reactions Conserve Mass Mass cannot be created or destroyed by a chemical or physical change Equations must be balanced. ?Na + ?H 2 O  ?NaOH + ?H 2 Section 2 Balancing Chemical Equations Chapter 8

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Balancing Equations The number of atoms for each element must be the same on the reactants’ side and on the products’ side. A coefficient multiplies the number of atoms of each element in the formula that follows. H 2 O: 2 hydrogen atoms, 1 oxygen atom 2H 2 O: 4 hydrogen atoms, 2 oxygen atoms Section 2 Balancing Chemical Equations Chapter 8

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Reading a Chemical Equation Chapter 8

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Balancing a Chemical Equation by Inspection Chapter 8

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Balancing Equations Sample Problem A Balance the equation for the reaction of iron(III) oxide with hydrogen to form iron and water. Section 2 Balancing Chemical Equations Chapter 8

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Balancing Equations Sample Problem A Solution 1.Identify reactants and products. reactants products Section 2 Balancing Chemical Equations ReactantsProductsBalanced? Unbalanced formula equationFe 2 O 3 + H 2 Fe + H 2 O Iron atoms21no Oxygen atoms31no Hydrogen atoms22yes 332 Chapter 8 3.Insert coefficients. 2.Count atoms Fe 2 O 3 + H 2  Fe + H 2 O

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reactions Conserve Mass Balanced equations show mass conservation ?Na + ?H 2 O  ?NaOH + ?H 2 2Na + 2H 2 O  2NaOH + H 2 Never change subscripts to balance equations Unbalanced: H 2 + O 2  H 2 O Incorrect:H 2 + O 2  H 2 O 2 H 2 O  H 2 O 2 Correct:2H 2 + O 2  2H 2 O Section 2 Balancing Chemical Equations Chapter 8

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reactions Conserve Mass Section 2 Balancing Chemical Equations Chapter 8

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Polyatomic Ions can be balanced as a group Section 2 Balancing Chemical Equations Chapter 8

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Balancing Equations Sample Problem C Aluminum reacts with arsenic acid, HAsO 3, to form H 2 and aluminum arsenate. Write a balanced equation for this reaction. Section 2 Balancing Chemical Equations Chapter 8

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Balancing Equations Sample Problem C Solution 1. Identify reactants and products. reactants products Al + HAsO 3  H 2 + Al(AsO 3 ) 3 2. Count Atoms Section 2 Balancing Chemical Equations ReactantsProductsBalanced? Unbalanced formula equationAl + HAsO 3 H 2 + Al(AsO 3 ) 3 Iron atoms 11yes Oxygen atoms 12no Hydrogen atoms 13no 3226 Chapter 8 3. Insert coefficients

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Bellringer Describe the following terms. synthesis decomposition displacement Chapter 8

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Objectives Identify combustion reactions, and write chemical equations that predict the products. Identify synthesis reactions, and write chemical equations that predict the products. Identify decomposition reactions, and write chemical equations that predict the products. Chapter 8

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Objectives, continued Identify displacement reactions, and use the activity series to write chemical equations that predict the products. Identify double-displacement reactions, and write chemical equations that predict the products. Chapter 8

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Combustion Reactions A combustion reaction is a reaction of a carbon- based compound with oxygen. Combustion of propane: C 3 H 8 + 5O 2  3CO 2 + 4H 2 O Combustion of ethanol: CH 3 CH 2 OH + 3O 2  2CO 2 + 3H 2 O Chapter 8

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Chapter 8 Combustion Reaction

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Synthesis Reactions In a synthesis reaction a single compound forms from two or more reactants. Two elements form a binary compound C + O 2  CO 2 2C + O 2  2CO Two compounds form a ternary compound CaO(s) + H 2 O(l)  Ca(OH) 2 (s) CO 2 (g) + H 2 O(l)  H 2 CO 3 (aq) Chapter 8

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Chapter 8 Synthesis Reactions

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Decomposition Reactions In a decomposition reaction a single compound breaks down, often with the input of energy, into two or more elements or simpler compounds. Decomposition of water electricity heat Chapter 8 CaCO 3 (s)CaO(s) + CO 2 (g) A metal carbonate decomposes to form a metal oxide and carbon dioxide. 2H 2 O(l)O 2 (g) + 2H 2 (g)

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Chapter 8 Decomposition Reaction

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Electrolysis Chapter 8

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Decomposition Reactions, continued Sample Problem D Predicting Products Predict the product(s) and write a balanced equation for the reaction of potassium with chlorine. Chapter 8

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Decomposition Reactions, continued Sample Problem D Solution Reaction is most likely a synthesis reaction, so the product will be binary Potassium will lose one electron to become a 1+ ion. Chlorine will gain one electron to become a 1– ion. K + Cl 2  KCl Balance the equation. 2K + Cl 2  2KCl Chapter 8

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Displacement Reactions In a displacement reaction a single element reacts with a compound and displaces another element from the compound. 2Al(s) + 3CuCl 2 (aq)  2AlCl 3 (aq) + 3Cu(s) Aluminum displaces copper. Chapter 8

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Single Displacement Reaction Chapter 8

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Displacement Reactions, continued The activity series ranks the reactivity of elements Chapter 8

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Activity Series Chapter 8

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Displacement Reactions, continued Sample Problem E Determining Products by Using the Activity Series Magnesium is added to a solution of lead(II) nitrate. Will a reaction happen? If so, write the equation and balance it. Chapter 8

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Displacement Reactions, continued Sample Problem E Solution 1.Identify the reactants. Magnesium will attempt to displace lead from lead(II) nitrate. 2.Check the activity series. Magnesium is more active than lead and displaces it. 3.Write the balanced equation. Mg + Pb(NO 3 ) 2  Pb + Mg(NO 3 ) 2 Chapter 8

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Classifying Chemical Reactions Double-Displacement Reactions In a double-displacement reaction two compounds in aqueous solution appear to exchange ions and form two new compounds. One of the products must be a solid precipitate, a gas, or a molecular compound, such as water. HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq) Chapter 8

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Chapter 8 Double-Displacement Reaction

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Precipitation Reaction Chapter 8

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Identifying Reactions and Predicting Products Chapter 8

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Bellringer Write a definition for the word spectator in terms of the part spectators play in a sporting event. Chapter 8

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Objectives Write total ionic equations for reactions in aqueous solutions. Identify spectator ions and write net ionic equations for reactions in aqueous solutions. Chapter 8

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Ionic Equations, continued Chapter 8 Ionic compounds dissolve in water KI(aq) = K + (aq) + I – (aq) Pb(NO 3 ) 2 (aq) = Pb 2+ (aq) + (aq) Reaction between KI and Pb(NO 3 ) 2 2KI(aq) + Pb(NO 3 ) 2 (aq)  PbI 2 (s) + 2KNO 3 (aq) Total Ionic Equation 2K + (aq) + 2I – (aq) + Pb 2+ (aq) + (aq)  PbI 2 (s) + 2K + (aq) + (aq)

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Ionic Equations, continued Chapter 8 Spectator ions remain unchanged in the solution as aqueous ions. They do not react. 2K + (aq) + 2I – (aq) + Pb 2+ (aq) + (aq) The net ionic equation is the chemical equation that shows only the net change. 2I – (aq) + Pb 2+ (aq)  PbI 2 (s)  PbI 2 (s) + 2K + (aq) + (aq)

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Net Ionic Equation Chapter 8

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Ionic Equations, continued Chapter 8 Net Ionic equations can be used for displacement reactions. Zn(s) + Cu 2+ (aq) + (aq)  Cu(s) + Zn 2+ (aq) + (aq) net ionic equation Zn(s) + Cu 2+ (aq)  Cu(s) + Zn 2+ (aq)

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Writing Net Ionic Equations Ionic Equations, continued Chapter 8 Check atoms and charge to balance net ionic equations. (aq) + Ba 2+ (aq)  BaSO 4 (s) Charge: (2–) + (2+) = 0 0 Zn(s) + Cu 2+ (aq)  Cu(s) + Zn 2+ (aq) Charge: 2+ 2+

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Writing a Net Ionic Equation Chapter 8

60. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Understanding Concepts Chapter 8 1.What type of chemical reaction involves the exchange of the ions of two compounds in an aqueous solution to form two new compounds? A.synthesis reaction B.decomposition reaction C.single-displacement reaction D.double-displacement reaction

61. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts Chapter 8 Standardized Test Preparation 2.Which of these sentences correctly states the law of conservation of mass? F.In a chemical reaction, the mass of the products cannot exceed the mass of the reactants. G.In a chemical reaction, the mass of the products is always equal to the mass of the reactants. H.In a chemical reaction, the mass of the products is always less than the mass of the reactants. I.In a chemical reaction, the mass of the products is always greater than the mass of the reactants.

62. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3.Of these reaction types, which has only one reactant? A.decomposition B.displacement C.oxidation D.synthesis Understanding Concepts Chapter 8 Standardized Test Preparation

63. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 4.Write a net ionic equation, excluding spectator ions, for the reaction: Mg(s) + Zn(NO 3 ) 2 (aq)  Zn(s) + Mg(NO 3 ) 2 (aq) Understanding Concepts Chapter 8 Standardized Test Preparation

64. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 5.Differentiate between formula equations and balanced chemical equations. Understanding Concepts Chapter 8 Standardized Test Preparation

65. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 6.Write a balanced equation for this reaction: iron(III) nitrate + lithium hydroxide  lithium nitrate + iron(III) hydroxide Chapter 8 Standardized Test Preparation Understanding Concepts

66. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Read the passage below. Then answer the questions. A student places a strip of pure magnesium metal into a test tube containing a dilute solution of hydrochloric acid (hydrogen chloride dissolved in water). As the magnesium disappears, bubbles of a colorless gas form and the test tube becomes hot to the touch. If a lit match is placed near the top of the test tube, the gas that has been generated burns. Reading Skills Chapter 8 Standardized Test Preparation

67. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 7.What evidence is there that a chemical reaction has occurred? Reading Skills Chapter 8 Standardized Test Preparation

68. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 8.Based on the substances present in the reaction, what is the most likely identity of the reaction product that burns in air? F.hydrogen G.magnesium H.oxygen I.oxygen and hydrogen mixture Reading Skills Chapter 8 Standardized Test Preparation

69. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 9.Which of these equations is a balanced chemical equation for the reaction described above? A.Mg(s) + HCl(aq)  MgCl 2 (aq) + H 2 (g) + energy B.Mg(s) + 2HCl(aq) + energy  MgCl 2 (aq) + H 2 (g) C.Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) + energy D.2Mg(s) + 2HCl(aq)  2MgCl 2 (aq) + H 2 (g) + energy Reading Skills Chapter 8 Standardized Test Preparation

70. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The table below shows the reactivity of selected elements. Use it to answer questions 10 through 12. Interpreting Graphics Chapter 8 Standardized Test Preparation

71. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 10.Which of these elements will produce a flammable product when placed in water at room temperature? F.aluminum G.silver H.sodium I.zinc Interpreting Graphics Chapter 8 Standardized Test Preparation

72. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 11.Which of these combinations is most likely to cause a displacement reaction? A.a zinc strip placed in a solution of aluminum chloride B.a nickel strip placed in a solution of calcium chloride C.a silver strip placed in a solution of potassium hydroxide D.an aluminum strip placed in a solution of copper chloride Interpreting Graphics Chapter 8 Standardized Test Preparation

73. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 12.What determines the order of the elements in the activity series? F.increasing atomic number G.increasing electronegativity H.increasing ionization energy I.experimentally determined reactivity Interpreting Graphics Chapter 8 Standardized Test Preparation