2. DEFINITION OF REACTION a chemical process in which two or more substances act mutually on each other and are changed into different substances Same as saying “combine” Exp. Iron (Fe) + Oxygen (O 2 ) = rust

3. 3 Physical Change Changes in physical properties melting boiling Condensation No change occurs in the identity of the substance Exp: Ice, rain, and steam are all water

4. LecturePLUS Timberlake4 Chemical Change Atoms in the reactants are rearranged to form one or more DIFFERENT & NEW substances Old bonds are broken  new bonds form Exp: Fe and O 2 form rust (Fe 2 O 3 ) Ag and S form tarnish (Ag 2 S)

5. Indicators of chemical reactions Formation of a gas Emission of light or heat Formation of a precipitate Color change Emission of odor

6. LecturePLUS Timberlake6 Learning Check E1 Classify each of the following as a 1) physical change or 2) chemical change A. ____ a burning candle B. ____ melting ice C. ____ toasting a marshmallow D. ____ cutting a pizza E. ____ polishing silver

7. LecturePLUS Timberlake7 Solution E1 Classify each of the following as a 1) physical change or 2) chemical change A. __2__ a burning candle B. __1_ melting ice C. __2__ toasting a marshmallow D. __1__ cutting a pizza E. __2__ polishing silver

8. LecturePLUS Timberlake8 Chemical Reaction A process in which at least one new substance is produced as a result of chemical change.

9. All chemical reactions: have 2 parts Reactants - the substances you start with Products- the substances you end up with The reactants turn into the products. Reactants  Products

10. LecturePLUS Timberlake10 A Chemical Reaction Reactants Products

11. Describing chemical reaction The way atoms are joined is changed Atoms aren’t created or destroyed. Can be described several ways: In a sentence Copper reacts with chlorine to form copper (II) chloride. In a word equation Copper + chlorine  copper (II) chloride Both still mean the same thing: Cu (s) + Cl 2 (g)  CuCl 2 (aq)

12. LecturePLUS Timberlake12 Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction ReactantsProducts MgO + CCO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

13. 13 Matter Is Conserved H 2 + Cl 2 2 HCl ++ Total atoms=Total atoms 2 H, 2 Cl2H, 2 Cl Total Mass=Total Mass 2(1.0) + 2(35.5)2(36.5) 73.0 g=73.0 g

14. LecturePLUS Timberlake14 Law of Conservation of Mass In any ordinary chemical reaction, matter is not created nor destroyed

15. Symbols used in equations (s) after the formula – solid = Cu (s) (g) after the formula – gas = H 2 (g) (l) after the formula - liquid = H 2 O (l) (aq) after the formula - dissolved in water, an aqueous solution. = CaCl 2 (aq)

16. Symbols used in equations  used after a product indicates a gas (same as (g)) = O 2   used after a product indicates a solid (same as (s)) = CaCo 3   indicates a reaction occurred or something is produced/yielded

17. Symbols used in equations indicates a reversible reaction. shows that heat is supplied to the reaction., or is used to indicate a catalyst used, in this case, platinum., indicates a pressure other than STP

18. Summary of Symbols

19. LecturePLUS Timberlake19 Learning Check E3 12 oz of dough, 4 oz mushrooms, 12 slices pepperoni, 8 oz cheese and 5 oz tomato sauce are used to make a pizza. Write a recipe in words for putting together a pizza. How would you write the recipe as an equation?

20. LecturePLUS Timberlake20 Solution E3 Example: Combine 12 oz dough + 4 oz mushrooms + 12 slices pepperoni + 8 oz cheese + 5 oz tomato sauce and heat 30 minutes at 350°C to produce 1 pizza 12 oz dough + 4 oz mshrm + 12 pep + 8 oz chse 1 pizza + 5 oz tom sauce

21. LecturePLUS Timberlake21 Reading A Chemical Equation 4 NH 3 + 5 O 2 4 NO + 6 H 2 O Four molecules of NH 3 react with five molecules O 2 to produce four molecules NO and six molecules of H 2 O or Four moles NH 3 react with five moles O 2 to produce four moles NO and six moles H 2 O

22. LecturePLUS Timberlake22 A Balanced Chemical Equation Same numbers of each type of atom on each side of the equation Al + S Al 2 S 3 Not Balanced 2Al + 3S Al 2 S 3 Balanced

23. LecturePLUS Timberlake23 Balance Equations with Coefficients Coefficients in front of formulas balance each type of atom 4NH 3 + 5O 2 4NO + 6H 2 O 4 N = 4 N 12 H=12 H 10 O=10 O

24. LecturePLUS Timberlake24 Steps in Balancing An Equation (focus on one atom at a time) Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O:Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

25. LecturePLUS Timberlake25 Learning Check E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 1) 22) 43) 8 B. Number of O atoms in 4 H 2 O 1) 22) 43) 8 C. Number of Fe atoms in Fe 3 O 4 1) 12) 33) 4

26. LecturePLUS Timberlake26 Solution E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 3) 8 B. Number of O atoms in 4 H 2 O 2) 4 C. Number of Fe atoms in Fe 3 O 4 2) 3

27. LecturePLUS Timberlake27 Learning Check E5 Balance each equation. The coefficients for each equation are read from left to right A. Mg + N 2 Mg 3 N 2 1) 1, 3, 2 2) 3, 1, 2 3) 3, 1, 1 B. Al + Cl 2 AlCl 3 1) 3, 3, 22) 1, 3, 13) 2, 3, 2

28. LecturePLUS Timberlake28 Learning Check E5 C. Fe 2 O 3 + C Fe + CO 2 1) 2, 3, 2,3 2) 2, 3, 4, 3 3) 1, 1, 2, 3 D. Al + FeO Fe + Al 2 O 3 1) 2, 3, 3, 1 2) 2, 1, 1, 1 3) 3, 3, 3, 1 E. Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 1) 3, 2, 1, 2 2) 2, 3, 1, 3 3) 2, 3, 2, 3

29. LecturePLUS Timberlake29 Solution E5 A. 3 Mg +N 2 Mg 3 N 2 B. 2 Al + 3 Cl 2 2 AlCl 3 C. 2 Fe 2 O 3 + 3 C 4 Fe + 3 CO 2 D. 2 Al + 3 FeO 3 Fe + Al 2 O 3 E. 2 Al + 3 H 2 SO 4 Al 2 (SO 4 ) 3 + 3 H 2

31. Counting with Moles Avogadro’s # - 6.02 x 10 23 Because chemical reactions often involve LARGE numbers of SMALL particles, chemists use a counting unit called  mole to measure amounts Exp. A mole of Iron (Fe) is 6.02 x 10 23 atoms of Iron

32. Molar Mass The mass of one mole of a substance is called the MOLAR MASS For an element, the molar mass is the same as the atomic mass expressed in grams (g) Exp. Atomic mass of carbon is 12.0 amu (found on the periodic table) so the molar mass of carbon is 12.0 grams

33. Molar Mass in Compounds Calculate the molar mass by adding up the atomic masses of its atoms and then convert to grams Exp. Carbon dioxide CO 2 – 1 atom of carbon & 2 atoms of oxygen 1 carbon atom (12.0 amu) + 2 oxygen atoms (2 x 16.0 amu = 32.0 amu) Total molar mass = 44.0 grams

34. Mole-Mass Conversions Once you know the molar mass of a substance, you can convert moles of that substance into mass or a mass of that substance into moles

35. Mole-Mass Example Molar mass of CO 2 = 44.0 grams (12.0 + (2x16.0) = 44.0 g This means that 1 mole of CO 2 = mass of 44.0 g 44.0 g CO 2 / 1 mol CO 2 or 1 mol CO 2 / 44.0 g CO 2 Suppose you have 55.0 g of CO 2. Calculate how many moles of CO 2 you have: 55.0 g CO 2 x 1 mol CO 2 / 44.0 g CO 2 = 1.25 mol CO 2 (Check your answer: 1.25 mol CO2 x 44.0g CO2 / 1 mol CO2 = 55.0 g CO2)

36. Chemical Equations In chemical reactions the mass of a reactant or product can be calculated by using: Balanced chemical equation – tells you how to relate amounts of reactants to amounts of products Molar masses of the reactants and products – lets you convert amounts into masses

37. Converting Mass to Moles Calculate how much oxygen is required to make 144 g of H 2 O: Determine how many moles of water you are trying to make 144 g H 2 O x 1 mol H 2 O / 18.0 g H 2 O = 8.00 mol H 2 O Copy down chart on page 197

39. Chemical Reactions Can be determined by: Type of reactant or # of reactants and products

40. Types of Chemical Reactions 1. Synthesis reactions 2. Decomposition reactions 3. Single displacement reactions 4. Double displacement reactions 5. Combustion reactions

41. 1. Synthesis Example C + O 2 OO C +  OO C General: A + B  AB

42. Ex. Synthesis Reaction

43. Practice Predict the products. Na (s) + Cl 2(g)  Mg (s) + F 2(g)  Al (s) + F 2(g)  NaCl (s) MgF 2(s) AlF 3(s) 2 2 232 Now, balance them.

44. 2. Decomposition Example: NaCl General: AB  A + B  Cl Na Cl + Na

45. Ex. Decomposition Reaction

46. 3. Single Displacement Example: Zn + CuCl 2  Zn Cl Cu + General: AB + C  AC + B Cl Zn Cu + Zn was oxidized Went from neutral (0) to (+2) Cu was reduced Went from (+2) to Neutral (0)

47. Ex. Single Replacement Reaction

48. Single Replacement Reactions Write and balance the following single replacement reaction equation: Zn (s) + HCl (aq)  ZnCl 2 + H 2(g) 2 NaCl (s) + F 2(g)  NaF (s) + Cl 2(g) Al (s) + Cu(NO 3 ) 2(aq)  22 Cu (s) + Al(NO 3 ) 3(aq) 3 23 2

49. 4. Double displacement Example: MgO + CaS General:AB + CD  AD + CB S O  Mg Ca + O S Mg Ca +

50. Double Replacement Reactions Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO 3(aq) + NaCl (s)  AgCl (s) + NaNO 3(aq) Another example: K 2 SO 4(aq) + Ba(NO 3 ) 2(aq)  KNO 3(aq) + BaSO 4(s) 2

51. Practice Predict the products. 1. HCl (aq) + AgNO 3(aq)  2. CaCl 2(aq) + Na 3 PO 4(aq)  3. Pb(NO 3 ) 2(aq) + BaCl 2(aq)  4. FeCl 3(aq) + NaOH (aq)  5. H 2 SO 4(aq) + NaOH (aq)  6. KOH (aq) + CuSO 4(aq) 

52. 5. Combustion Reactions Combustion reactions - a hydrocarbon reacts with oxygen gas. This is also called burning!!! In order to burn something you need the 3 things in the “fire triangle”: 1) Fuel (hydrocarbon) 2) Oxygen 3) Something to ignite the reaction (spark)

53. Combustion Reactions In general: C x H y + O 2  CO 2 + H 2 O Products are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by-products like carbon monoxide) Combustion is used to heat homes and run automobiles (octane, as in gasoline, is C 8 H 18 )

54. Combustion Example C 5 H 12 + O 2  CO 2 + H 2 O Write the products and balance the following combustion reaction: C 10 H 22 + O 2  5 6 8

55. Mixed Practice State the type & predict the products. 1. BaCl 2 + H 2 SO 4  2. C 6 H 12 + O 2  3. Zn + CuSO 4  4. Cs + Br 2  5. FeCO 3 

56. Synthesis Reactions Also called combination reactions 2 elements, or compounds combine to make one compound. A + B  AB Na (s) + Cl 2 (g)  NaCl (s) Ca (s) +O 2 (g)  CaO (s) SO 3 (s) + H 2 O (l)  H 2 SO 4 (s) We can predict the products if they are two elements. Mg (s) + N 2 (g)  Mg 3 N 2 (s)

57. A simulation of the reaction: 2H 2 + O 2  2H 2 O

58. Decomposition Reactions decompose = fall apart one compound (reactant) falls apart into two or more elements or compounds. Usually requires energy AB  A + B NaCl Na + Cl 2 CaCO 3 CaO + CO 2

59. Can predict the products if it is a binary compound Made up of only two elements Falls apart into its elements H2OH2O HgO Decomposition Reactions H 2 (g) + O 2 (g) Hg (s) + O 2 (g)

60. If the compound has more than two elements you must be given one of the products The other product will be from the missing pieces NiCO 3 (aq) H 2 CO 3 (aq)  + Ni (s) + CO 2 (g) Decomposition Reactions CO 2 (g) H 2 (g)

61. Single Replacement Also referred to as single displacement One element replaces another Reactants must be an element and a compound. Products will be a different element and a different compound. A + BC  AC + B 2Na + SrCl 2  Sr + 2NaCl F 2 + LiCl  LiF + Cl 2

62. Single Replacement We can tell whether a reaction will happen Some are more active than other More active replaces less active

63. Double Replacement Two things replace each other. Reactants must be two ionic compounds or acids. Usually in aqueous solution AB + CD  AD + CB AgNO 3 + NaCl  AgCl + NaNO 3 ZnS + 2HCl  ZnCl + H 2 S

64. Combustion A reaction in which a compound (often carbon) reacts with oxygen CH 4 + O 2  CO 2 + H 2 O C 3 H 8 + O 2  CO 2 + H 2 O C 6 H 12 O 6 + O 2  CO 2 + H 2 O

65. The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction is C + O 2  CO 2

66. Acid/Base Reaction An acid and a base react to form a salt and water. Always in aqueous solution Acid (H + ) + Base (OH - ) → Salt + H 2 O NaOH + HCl → NaCl + H 2 O NH 4 OH + H 2 SO 4 → (NH 4 ) 2 SO 4 + H 2 O

67. How to recognize which type Look at the reactants Element(E), Compound(C) E + E C E + C C + C Acid + Base Look at the Products CO 2 + H 2 O Redox Synthesis Decomposition Single replacement Double replacement Acid/Base reaction Combustion

68. Examples Synthesis Decomposition Single replacement Double replacement H 2 + O 2  H 2 O  AgNO 3 + NaCl  Zn + H 2 SO 4  HgO  KBr +Cl 2  Mg(OH) 2 + H 2 SO 3 

69. Examples Acid/Base Decomposition Single replacement Synthesis Acid/Base Single replacement Double replacement HNO 3 + KOH  CaPO 4  AgBr + Cl 2  Zn + O 2  HgO + Pb  HBr + NH 4 OH  Cu(OH) 2 + KClO 3 

70. Summary An equation: Describes a reaction Must be BALANCED because to follow Law of Conservation of Energy Can only be balanced by changing the coefficients. Has special symbols to indicate state, and if catalyst or energy is required. Can describe 5 different types of reactions.

71. Oxidation-Reduction Reaction A reaction in which electrons are transferred from one reactant to another. A.K.A. Redox Reaction

72. Oxidation Any process in which an element loses electrons during a chemical reaction A reactant is oxidized if it loses electrons Exp. 2Ca + O 2  2 CaO When calcium reacts with oxygen, each neutral calcium atom loses two electrons and becomes a calcium ion with a charge of +2

73. Reduction The process in which an element gains electrons during a chemical reaction A reactant is said to be reduced if it gains electrons Exp. O + 2e  O 2-

74. Redox Reactions Compare: Must happen together = when 1 atom loses e- another will gain it Contrast: Can be a partial transfer as in the synthesis of H 2 O “Sharing” Oxidation – loses electrons Reduction – gains electrons

75. Chemical Bonds and Energy Energy stored in the chemical bonds of a substance Exp. Propane – has 10 single covalent bonds; chemical energy of a propane molecule is the energy stored in these bonds

76. Importance of Chemical Reactions Chemical reactions involve the breaking of chemical bonds in the reactants and the formation of chemical bonds in the products Energy is either released or absorbed

77. Breaking Bonds Requires energy Exp. Why propane grills have an igniter, a device that produces a spark Spark provides enough energy to break the bonds of reacting molecules and get the reaction to start

78. Forming Bonds Releases energy Exp. The heat and light given off by a propane stove result from the formation of new chemical bonds

79. Exothermic and Endothermic Reactions Exothermic: Releases energy Energy released as the products form is greater than the energy required to break the bonds in the reactants Endothermic: Absorbs energy More energy is required to break the bonds in the reactants than is released by the formation of the products

81. All chemical reactions are accompanied by a change in energy. Exothermic - reactions that release energy to their surroundings (usually in the form of heat) oΔH (enthalpy) is negative – energy leaving system Endothermic - reactions that need to absorb heat from their surroundings to proceed. oΔH (enthalpy) is positive – energy coming into the system Reaction Energy

82. Law of Conservation of Energy Exothermic – chemical energy of the reactants is converted into heat plus the chemical energy of the products Endothermic – heat plus the chemical energy of the reactants is converted into the chemical energy of the products Both cases = total amount of energy is the same before and after the reaction

83. Reaction Rate Rate at which reactants change into products over time Tell you how fast a reaction is going Exp. Burning calories Calories – unit of energy used in nutrition Pg. 212 in textbook

84. Factors affecting Reaction Rates Temperature Surface area Concentration Stirring Catalysts

85. Temperature Generally an increase in temperature will increase the reaction rate and vice versa Increasing the temperature causes the particles to move faster which are thus more likely to collide and more likely to react

86. Surface Area Smaller the particle size of a given mass, the larger is its surface area Increase in surface area increases the exposure of reactants to one another The greater the exposure, the more collisions there are that involve reacting particles – more collisions = more reactions

87. Stirring Stirring causes collisions between particles of the reactants Exp. Clothes in a washing machine

88. Concentration Refers to the # of particles in a given volume The more reacting particles that are present in the given volume, the more opportunities there are for collisions involving those particles

89. Catalysts A substance that speeds up a reaction without being used up or changed by the reaction. Often used to speed up a reaction or enable a reaction to occur at a lower temp. Lower the energy barrier (activation energy) required for a reaction to take place

90. Spontaneous Reactions - Reactions that proceed immediately when two substances are mixed together. Not all reactions proceed spontaneously. Reaction Energy Activation Energy – the amount of energy that is required to start a chemical reaction. Once activation energy is reached the reaction continues until you run out of material to react.