1. 2.C – Conserving Matter

2. 2C.1- Keeping Track of Atoms

3. When a car’s gas empties, where do the atoms in the gasoline go?

4. Keeping Track of Atoms  Law of Conservation of Matter: Matter is neither created nor destroyed.  Since chemical reactions cannot create or destroy atoms, chemical equations representing the reactions must always be BALANCED.

5. Atomic Perspective: C O 2  CO 2 1 Carbon atom 1 oxygen molecule  1 carbon dioxide molecule 1.What are the reactants in this chemical equation? 2.What are the products in this chemical equation? 3.Are there the same number of atoms on both sides of the equation? a.Where any atoms destroyed or created? b.Was the Law of Conservation of Matter maintained?

6. 2 Cu (s) + O 2 (g)  2 CuO (s) COEFFICIENTS - indicates the number of units of each substance involved. 1.Does the oxygen molecule have a coefficient? 2.What do the subscripts represent? 3.Can subscripts be removed from chemical equations?

7. How do we Balance Equations? 2 H 2 + O 2  2 H 2 O Subscripts Coefficients # of atoms in a compound Number of compounds in the reaction Subscripts balance charges within a compound. Coefficients balance atoms in an equation

8. What do Coefficients Really Mean? CH 4 + 2 O 2  CO 2 + 2 H 2 O Total: 1 C 4 H 4 O Total: 1 C 4 H 4 O The equation is balanced.

9. 2 C.2-C.3 - Accounting for atoms - Nature’s conservation: Balanced chemical equations

10. How to Balance By Inspection: Taken from Kelly Deters Make a table of elements _____ 1 Reactants Products H O C CH4H4 + O2O2  H2H2 OCO2O2 +_____

11. How to Balance By Inspection: Taken from Kelly Deters 2 Count the number of each element or ion on the reactants and products side. _____ Reactants Products H O 4 23 2 C11 CH4H4 + O2O2  H2H2 OCO2O2 +_____ Don’t forget to add all the atoms of the same element together— even if it appears in more than one compound!

12. How to Balance By Inspection: Taken from Kelly Deters 3 Each time you add a coefficient, update your table with the new quantities of each atom. Add coefficients to balance the numbers _____ 2 Reactants Products H O 4 23 2 C11 2 4 44 CH4H4 + O2O2  _____H2H2 OCO2O2 +

13. How to Balance By Inspection: Taken from Kelly Deters 4 Filling each coefficient location lets you and the grader know that you finished the problem rather than you left some blank because you weren’t done! Place a “1” in any empty coefficient location _____ 2 Reactants Products H O 4 23 2 C11 2 4 44 11CH4H4 + O2O2  _____H2H2 OCO2O2 +

14. Choosing the Order of Balancing Taken from Kelly Deters Save for later Elements that are uncombined Save for later Elements that appear more than 1 time per side Start Elements that appear only 1 time per side Start Elements in most complicated molecules How do you know what order to balance in? Pb + PbO 2 + H +  Pb 2+ + H 2 O To balance this equation, use the order: O, H, Pb

15. How is Balancing Affected by Order? Taken from Kelly Deters _____ What happens if we balance in the order determined in the last slide? Reactants Products H Pb 1 21 2 O21 4 2 _____ 1212Pb +O2O2  H2H2 OPb 2+ + H+H+ _____4 + 2 4 O, H, Pb

16. What about a different order? Taken from Kelly Deters 2 _____ How is it different if we balance in a different order? Reactants Products O Pb 2 21 1 H1 2 2 _____ 1212Pb +O2O2  H2H2 OPb 2+ + H+H+ _____2 + 24 4 4  You’ll still get to the correct answer, but it will take longer and be more complicated! H, O, Pb

17. Let’s Practice #1 Taken from Kelly Deters Example: Balance the following equation __ HCl + __ Ca(OH) 2  __ CaCl 2 + __ H 2 O

18. Let’s Practice #1 Taken from Kelly Deters Example: Balance the following equation __ HCl + __ Ca(OH) 2  __ CaCl 2 + __ H 2 O 2112 HOH Did you see the “OH” polyatomic ion & change H 2 O to HOH?

19. Let’s Practice #2 Taken from Kelly Deters Example: Balance the following equation __ H 2 + __ O 2  __ H 2 O

20. Let’s Practice #2 Taken from Kelly Deters Example: Balance the following equation __ H 2 + __ O 2  __ H 2 O 212

21. Let’s Practice #3 Taken from Kelly Deters Example: Balance the following equation __ Fe + __ O 2  ___ Fe 2 O 3

22. Let’s Practice #3 Taken from Kelly Deters Example: Balance the following equation __ Fe + __ O 2  ___ Fe 2 O 3 432

23. C.5 The Mole Concept Definition: Mole – SI unit for counting Adopted from "Chemistry You Need to Know" by Kelly Deters

24. What is a counting unit? Adopted from "Chemistry You Need to Know" by Kelly Deters You’re already familiar with one counting unit…a “dozen” “Dozen”12 A dozen doughnuts 12 doughnuts A dozen books A dozen cars A dozen people 12 books 12 cars 12 people A dozen = 12

25. How big is a mole?  Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles.  If you had Avogadro's number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles.  If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole. Adopted from "Chemistry You Need to Know" by Kelly Deters

26. A Mole of Particles A Mole of Particles Contains 6.02 x 10 23 particles 1 mole C = 6.02 x 10 23 C atoms 1 mole H 2 O = 6.02 x 10 23 H 2 O molecules 1 mole NaCl= 6.02 x 10 23 NaCl “molecules” Adopted from "Chemistry You Need to Know" by Kelly Deters

27. What does a “mole” count in? Adopted from "Chemistry You Need to Know" by Kelly Deters A mole = 6.02  10 23 (called Avogadro’s number) “mole” 6.02  10 23 1 mole of doughnuts 6.02  10 23 doughnuts 1 mole of atoms 1 mole of molecules 6.02  10 23 atoms 6.02  10 23 molecules 6.02  10 23 = 602,000,000,000,000,000,000,000

28. C. 6 Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters

29. Definition Adopted from "Chemistry You Need to Know" by Kelly Deters Molar Mass – The mass for one mole of an atom or molecule. Other terms commonly used for the same meaning: Molecular Weight Molecular Mass Formula Weight Formula Mass

30. Mass for 1 mole of atoms Adopted from "Chemistry You Need to Know" by Kelly Deters The average atomic mass = grams for 1 mole ElementMass 1 mole of carbon atoms 12.01 g 1 mole of oxygen atoms 1 mole of hydrogen atoms 16.00 g 1.01 g Unit for molar mass: g/mole or g/mol Average atomic mass is found on the periodic table

31. Molar mass for molecules Adopted from "Chemistry You Need to Know" by Kelly Deters The molar mass for a molecule = the sum of the molar masses of all the atoms

32. Calculating a Molecule’s Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Count the number of each type of atom Find the molar mass of each atom on the periodic table Multiple the # of atoms  molar mass for each atom Find the sum of all the masses 1 2 3 4 To find the molar mass of a molecule:

33. Example: Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Example: Find the molar mass for CaBr 2

34. Example: Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Count the number of each type of atom 1 Ca Br 1 2 Example: Find the molar mass for CaBr 2

35. Example: Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Find the molar mass of each atom on the periodic table 2 Ca Br 1 2 40.08 g/mole 79.91 g/mole Example: Find the molar mass for CaBr 2

36. Example: Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Multiple the # of atoms  molar mass for each atom 3 Ca Br 1 2 40.08 g/mole 79.91 g/mole   Example: Find the molar mass for CaBr 2 = 40.08 g/mole = 159.82 g/mole

37. Example: Molar Mass Adopted from "Chemistry You Need to Know" by Kelly Deters Find the sum of all the masses 4 Ca Br 1 2 40.08 g/mole 79.91 g/mole = 40.08 g/mole = 159.82 g/mole + 199.90 g/mole 1 mole of CaBr 2 molecules would have a mass of 199.90 g Example: Find the molar mass for CaBr 2  

38. Example: Molar Mass & Parenthesis Adopted from "Chemistry You Need to Know" by Kelly Deters Be sure to distribute the subscript outside the parenthesis to each element inside the parenthesis. Example: Find the molar mass for Sr(NO 3 ) 2

39. Example: Molar Mass & Parenthesis Adopted from "Chemistry You Need to Know" by Kelly Deters Be sure to distribute the subscript outside the parenthesis to each element inside the parenthesis. 1 6 87.62 g/mole 16.00 g/mole   = 87.62 g/mole = 96.00 g/mole + 211.64 g/mole 1 mole of Sr(NO 3 ) 2 molecules would have a mass of 211.64 g 214.01 g/mole  = 28.02 g/mole Sr N O Example: Find the molar mass for Sr(NO 3 ) 2

40. Let’s Practice #2 Adopted from "Chemistry You Need to Know" by Kelly Deters Example: Find the molar mass for Al(OH) 3

41. Let’s Practice #2 Adopted from "Chemistry You Need to Know" by Kelly Deters Be sure to distribute the subscript outside the parenthesis to each element inside the parenthesis. 1 3 26.98 g/mole 1.01 g/mole   = 26.98 g/mole = 3.03 g/mole + 78.01 g/mole 1 mole of Al(OH) 3 molecules would have a mass of 78.01 g 316.00 g/mole  = 48.0 g/mole Al O H Example: Find the molar mass for Al(OH) 3

43. C.8 Molar Relationships

44. Equations and Molar Relationships $1.00 = 4 quarters If you have 12 quarters than how many $$$’s is that equal to? Adopted from "Chemistry You Need to Know" by Kelly Deters

45. Equations and Molar Relationships $1.00 = 4 quarters If you have 12 quarters than how many $$$’s is that equal to? $3.00

46. 2 H 2 + O 2  2 H 2 O 2 No coefficient = 1 2 For every 2 moles of H 2 … 1 mole of O 2 is need to react… 2 moles of H 2 O are produced What do those coefficients really mean? 1.What relationships can be found in this equation?

47. Stoichiometry with Moles Example: If 4 moles of H 2 reacts completely with O 2, how many moles of O 2 are needed? 2 H 2 + O 2  2 H 2 O

48. Stoichiometry with Moles 4 mole H 2 mole H 2 mole O 2 = ________ mole O 2 2 1 2 From balanced equation: 2 mole H 2  1 mole O 2 Example: If 4 moles of H 2 reacts completely with O 2, how many moles of O 2 are needed? 2 H 2 + O 2  2 H 2 O

49. But we can’t measure moles in lab! We can’t go to the lab and count or measure moles…so we need a way to work in measurable units, such as grams and liters! Molecular mass gives the grams = 1 mole of a compound!

50. Stoichiometry with Moles & Mass Example: How many grams of AgCl will be precipitated if 0.45 mole AgNO 3 is reacted as follows: 2 AgNO 3 + CaCl 2  2 AgCl + Ca(NO 3 ) 2

51. From balanced equation: 2 mole AgNO 3  2 mole AgCl Stoichiometry with Moles & Mass 0.45 mole AgNO 3 mole AgNO 3 mole AgCl = ________ g AgCl 2 2 65 Molar Mass of AgCl: 1 mole AgCl = 143.35 g mole AgCl g AgCl 1 143.35 Example: How many grams of AgCl will be precipitated if 0.45 mole AgNO 3 is reacted as follows: 2 AgNO 3 + CaCl 2  2 AgCl + Ca(NO 3 ) 2

52. Stoichiometry with Mass Example: How many grams Ba(OH) 2 are precipitated from 14.5 g of NaOH in the following reaction: 2 NaOH + BaCl 2  Ba(OH) 2 + 2 NaCl

53. From balanced equation: 2 mole NaOH  1 mole Ba(OH) 2 Stoichiometry with Mass 14.5 g NaOH g NaOH mole NaOH = ________ g Ba(OH) 2 40.00 1 31.1 Molar Mass of NaOH: 1 mole NaCl = 40.00 g mole NaOH mole Ba(OH) 2 2 1 g Ba(OH) 2 1 171.35 Molar Mass of Ba(OH) 2 : 1 mole Ba(OH) 2 = 171.35 g Example: How many grams Ba(OH) 2 are precipitated from 14.5 g of NaOH in the following reaction: 2 NaOH + BaCl 2  Ba(OH) 2 + 2 NaCl

54. Let’s Practice #1 Example: If you are making 0.57 moles H 2 O, how many moles of O 2 are needed? 2 H 2 + O 2  2 H 2 O

55. Let’s Practice #1 0.57 mole H 2 O mole H 2 O mole O 2 = ________ mole O 2 2 1 0.29 From balanced equation: 2 mole H 2 O  1 mole O 2 Example: If you are making 0.57 moles H 2 O, how many moles of O 2 are needed? 2 H 2 + O 2  2 H 2 O

56. Let’s Practice #2 Example: If you need to precipitate 10.7 g of Ba(OH) 2, how many grams NaOH are needed? 2 NaOH + BaCl 2  Ba(OH) 2 + 2 NaCl

57. From balanced equation: 2 mole NaOH  1 mole Ba(OH) 2 Let’s Practice #2 10.7 g Ba(OH) 2 g Ba(OH) 2 mole Ba(OH) 2 = ________ g NaOH 171.35 1 5.00 Molar Mass of Ba(OH) 2 : 1 mole Ba(OH) 2 = 171.35 g mole Ba(OH) 2 mole NaOH 1 2 g NaOH 1 40.00 Molar Mass of NaOH: 1 mole NaCl = 40.00 g Example: If you need to precipitate 10.7 g of Ba(OH) 2, how many grams NaOH are needed? 2 NaOH + BaCl 2  Ba(OH) 2 + 2 NaCl

58. Let’s Practice #3 Example: How many moles AgNO 3 are needed to react with 10.7 g CaCl 2 ? 2 AgNO 3 + CaCl 2  2 AgCl + 2 Ca(NO 3 ) 2

59. From balanced equation: 2 mole AgNO 3  1 mole CaCl 2 Let’s Practice #3 10.7 g CaCl 2 g CaCl 2 mole CaCl 2 = ______ mole AgNO 3 110.98 1 0.193 Molar Mass of CaCl 2 : 1 mole CaCl 2 = 110.98 g mole CaCl 2 mole AgNO 3 1 2 Example: How many moles AgNO 3 are needed to react with 10.7 g CaCl 2 ? 2 AgNO 3 + CaCl 2  2 AgCl + 2 Ca(NO 3 ) 2

60. C.10 Percent Composition

61. How many different metals should we use for the coin design?  If using multiple metals, you:  A) Need to know specify how much each material is present  B) Use: Percentage by Mass of each material – Percentage Composition

62. USA - Penny  During 1943 - made of zinc coated steel  After 1943 to 1982 - mostly copper  Since 1982 - made primarily of Zinc

64. 2C.12 Conservation

65. Depleting Resources  Renewable resources  Nonrenewable resources  Q. If atoms are always conserved, how can we say that we may be “running out” of a resource?

66. Conserving Resources  Rethinking  Reusing  Replacing  Recycling

67. Recycling Aluminum

68. Dealing with Waste

69. 2C.14 The Life Cycle of a Material

70. Life Cycle of Paper