1. CHEMICAL REACTIONS Chapter 7

2. Changes PHYSICAL –Only affects the size, shape and state. –Amount of energy involved in each state varies. CHEMICAL –Atoms are rearranged. –Bonds broken –new substance created –Energy released or absorbed

3. Physical OR Chemical Reactions?

4. Lab: Conservation of Mass Physical or Chemical Change? A – Dissolving Salt and Water B – Melting Ice C – Lead nitrate mixed with sodium chloride OR sodium iodide D – copper and sulfur E – water and alka- seltzer

5. Lab: Conservation of Mass Physical or Chemical Change? A – Dissolving Salt and Water B – Melting Ice C – Lead nitrate mixed with sodium chloride OR sodium iodide D – copper and sulfur E – water and alka- seltzer Physical Chemical

6. Chemical Reactions Rearrange atoms REACTANTSPRODUCTS C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O New product atoms and old reactant atoms are not created or destroyed. Mass is always conserved.

7. Energy and Reactions Energy must be added to break bonds Energy –Heat –Electricity –Sound –light

8. Forming bonds releases energy Energy and Reactions

10. Examples Endothermic –Photosynthesis –Dissolving most salts into water (exceptions) –Decomposition reactions A –– > B + C Exothermic –Combustion of Methane (Natural Gas).Combustion of Methane –Adding concentrated sulfuric acid to water –Acid/Base reactions Dissolving a strong acid or strong base

11. Diatomic Molecules Most elemental gases do not exist as single atoms H 2 N 2 F 2 O 2 I 2 Cl 2 Br 2

12. 7.2 Chemical Reactions Are Represented by Chemical Equations 7.2 Chemical Reactions Are Represented by Chemical Equations

13. Chemical Equation A representation in which reactants are written before an arrow and products are written after the arrow.

14. Reactants Products

15. Reactants Substances that are about to chemically react.

16. Products Substances that are formed from a chemical reaction.

17. Animation “CO2flask.mov”

18. Reactants

19. Carbon,C Reactants

20. Carbon,C Oxygen, O 2 Reactants

21. Chemical reaction

22. Products

23. Carbon Dioxide, CO 2 Products

24. Coefficients Integers used to indicate the ratio by which reactants react and products form.

25. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + +

26. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + + 2 2

27. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + + 2 2 1 1

28. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + + 2 2 1 1 2 2

29. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + + 2 2 2 2

30. Reactants Products H2H2 H2H2 O2O2 O2O2 H2OH2O H2OH2O + + 2 2 2 2 (g)

31. Balancing Chemical Equations

32. Balancing Guidelines 1)Balance one element at a time. 1)Balance one element at a time. 2) If you incidentally unbalance an element leave it alone. 2) If you incidentally unbalance an element leave it alone. 3) Make successive passes.

33. Al 2 O 3 C C CO 2 + + Al + +

34. Al 2 O 3 C C CO 2 + + Al + + (not balanced)

35. Al 2 O 3 C C CO 2 + + Al + +

36. Al 2 O 3 C C CO 2 + + Al + + OOO C COO

37. Al 2 O 3 C C CO 2 + + Al + +

38. Al 2 O 3 C C CO 2 + + Al + + 2 2

39. Al 2 O 3 C C CO 2 + + Al + + OOO C COO 2 2

40. Al 2 O 3 C C CO 2 + + Al + + 2 2

41. Al 2 O 3 C C CO 2 + + Al + + 2 2 3 3 2 2

42. Al 2 O 3 C C CO 2 + + Al + + OOOC COO 2 2 3 3 2 2 COO COO OOO

43. Al 2 O 3 C C CO 2 + + Al + + 2 2 3 3 2 2

44. Al 2 O 3 C C CO 2 + + Al + + 2 2 3 3 2 2 3 3

45. Al 2 O 3 C C CO 2 + + Al + + OOOC COO 2 2 3 3 2 2 COO COO OOO 3 3 C C

46. Al 2 O 3 C C CO 2 + + Al + + 4 4 3 3 2 2 3 3 Balanced Al OOOC COO COO COO OOO C C

47. Al 2 O 3 C C CO 2 + + Al + + 4 4 3 3 2 2 3 3 Balanced

48. Na 2 SO 3 S8S8 S8S8 + + not balanced Na 2 S 2 O 3

49. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3

50. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 1 1 1 1

51. Na 2 SO 3 S1S1 S1S1 + + Na 2 S 2 O 3 1 1 1 1

52. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 1 1 1 1

53. 8 8 Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 1 1 1 1 1 1

54. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 S S S S S S S S S S S S S S S S 8 8 1 1 1 1 1 1

55. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 S S S S S S S S S S S S S S S S 8 8 1 1 1 1 1 1

56. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 S S S S S S S S S S S S S S S S 8 8 1 1 1 1 1 1

57. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 S S S S S S S S S S S S S S S S 8 8 1 1 1 1 1 1

58. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 1 1 1 1 1 1

59. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 1 1 1 1 1 1

60. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 1 1 8 8 1 1 1 1

61. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 8 8 8 8 1 1 8 8 x x

62. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 8 8 8 8 1 1 8 8 x x = = 1 1

63. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 8 8 8 8 1 1

64. Na 2 SO 3 S8S8 S8S8 + + Na 2 S 2 O 3 Balanced 8 8 8 8 1 1

65. 7.1 Chemical Reactions Are Represented by Chemical Equations 7.1 Chemical Reactions Are Represented by Chemical Equations

66. 7.2 Chemists Use Relative Masses to Count Atoms and Molecules 7.2 Chemists Use Relative Masses to Count Atoms and Molecules

67. TYPES OF REACTIONS Chapter 7

68. Types of Reaction 1. Addition Reactions (aka synthesis) A + B AB  2 or more substances combine to form a new compound.  small molecules join to form chains - polymerization Fe + O 2 Fe 2 O 3

69. Types of Reactions 2. Decomposition Reactions ABA + B  compounds are broken apart into smaller substances Example: Electrolysis of water 2 H 2 O 2 H 2 + O 2

70. Types of Reactions Single – Displacement Reaction –AX + BBX + A  One element replaces a similar element in a compound  Aka Single – Replacement Reaction

71. Types of Reactions Double – Displacement Reaction –AB + CDAD + CB  Aka double –replacement reactions  Ions from 2 compounds in solution exchange places to produce 2 new compounds.  One of the compounds is usually …  A precipitate  A gas that bubbles off  A molecular compound like water

72. Types of Reactions Combustion Reactions –These use O 2 as a reactant –One product contains O and the other usually H 2 O Carbon cpd. + O 2 CO 2 + H 2 O ___________________________________________________________________________________________________________________

73. Types of Reactions Combustion Reactions –These use O 2 as a reactant –One product contains O, usually H 2 O ____________________________________________________________________________________________________________________________ Importance of Good Air Supply 2CH 4 + 4O 2 2CO 2 + 4H 2 O 2CH 4 + 3O 2 2CO + 4H 2 O 2CH 4 + 2O 2 2C + 4H 2 O

74. Chapter 7.1 Energy in Reactions

75. Examples Endothermic –Melting of ice –evaporation of water – boiling of water. –Photosynthesis –Dissolving most salts into water (exceptions) –Decomposition reactions AB –– > A + B Exothermic –Combustion of Methane (Natural Gas).Combustion of Methane –Adding concentrated sulfuric acid to water –Acid/Base reactions Dissolving a strong acid or strong base

76. Other Terms - refers to the ease in which the reactions occurs Exergonic – Most cases: are exothermic –Bioluminescence –Respiration Endergonic –Most cases: are endothermic –Photosynthesis

77. Endothermic Reaction (ex. Photosynthesis) – takes in energy- cold pack Exothermic Reactions (ex. Cell Respiration) – gives off energy– hot pack Plus more balancing reactions to show conservation of mass and energy

78. __Cu+__O 2  __CuO __Cu+__S  __CuS H 2 O  2H 2 + O 2 CuCl 2 + Zn  ZnCl 2 + Cu HCl + NaOH  HOH + NaCl PbNO 3 + KI  PbI + KNO 3 PbNO 3 +NaCl  PbCl +NaNO 3 4CH 3 + 7O 2  4CO 2 + 6H 2 O 860 × 691 - fphoto.photoshelter.com60 × 691 - fphoto.photoshelter.com 605 × 500 - fphoto.com05 × 500 - fphoto.com

79. 2Cu+O 2  2CuO or Cu+S  CuS __H 2 O  __H 2 + __O 2 CuCl 2 + Zn  ZnCl 2 + Cu HCl + NaOH  HOH + NaCl PbNO 3 + KI  PbI + KNO 3 PbNO 3 +NaCl  PbCl +NaNO 3 4CH 3 + 7O 2  4CO 2 + 6H 2 O 448 × 420 - witcombe.sbc.edu48 × 420 - witcombe.sbc.edu

80. 2Cu+O 2  2CuO or Cu+S  CuS 2H 2 O  2H 2 + O 2 __CuCl 2 + __Zn  __ZnCl 2 + __Cu HCl + NaOH  HOH + NaCl PbNO 3 + KI  PbI + KNO 3 PbNO 3 +NaCl  PbCl +NaNO 3 4CH 3 + 7O 2  4CO 2 + 6H 2 O

81. 2Cu+O 2  2CuO or Cu+S  CuS 2H 2 O  2H 2 + O 2 CuCl 2 + Zn  ZnCl 2 + Cu __HCl + __NaOH  __HOH + __NaCl __PbNO 3 + __KI  __PbI + __KNO 3 __PbNO 3 +__NaCl  __PbCl +__NaNO 3 4CH 3 + 7O 2  4CO 2 + 6H 2 O

82. 2Cu+O 2  2CuO or Cu+S  CuS 2H 2 O  2H 2 + O 2 CuCl 2 + Zn  ZnCl 2 + Cu HCl + NaOH  HOH + NaCl PbNO 3 + KI  PbI + KNO 3 PbNO 3 +NaCl  PbCl +NaNO 3 __CH 4 + __O 2  __CO 2 + __H 2 O

83. Examples Endothermic –Melting of ice –evaporation of water – boiling of water. –Photosynthesis –Dissolving most salts into water (exceptions) –Decomposition reactions A –– > B + C Exothermic –Combustion of Methane (Natural Gas).Combustion of Methane –Adding concentrated sulfuric acid to water –Acid/Base reactions Dissolving a strong acid or strong base