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Unit 1: Stoichiometry

Unit 1: Stoichiometry

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Unit 1: Stoichiometry

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  1. Unit 1: Stoichiometry Chemistry 2202

  2. Stoichiometry Stoichiometry deals with quantities used in OR produced by a chemical reaction

  3. 3 Parts Mole Calculations (Chp. 2 & 3) Stoichiometry and Chemical Equations (Chp. 4) Solution Stoichiometry (Chp. 6)

  4. PART 1 - Mole Calculations Isotopes and Atomic Mass (pp. 43 - 46) Avogadro’s number (pp. 47 – 49) Mole Conversions (pp. 50 - 74) M, MV, NA, n, m, v, N

  5. Questions p. 45 #’s 1 – 4 p. 46 #’s 1 – 6 p. 75 #’s 9 – 12 p. 51-53 #’s 5 – 15 p. 57 #’s 16 – 19 p. 59,60 #’s 20 – 27 p. 63,64 #’s 28 - 37 p. 54 #’s 5 – 8 p. 65 #’s 2, 4, 5 p. 75 #’s 13, 14 p. 76 #’s 15, 17–19, 21-23 p. 73 #’s 38 – 43 p. 74 #’s 1 – 4 p. 76 #’s 26, 27

  6. PART 1 - Mole Calculations Percent composition: - given mass (p. 79 - 82) - given the chemical formula (p. 83 - 86) Empirical Formulas (pp. 87 - 94) Molecular Formulas (pp. 95 - 98) Lab: Formula of a Hydrate

  7. Questions p. 82 #’s 1 – 4 p. 85 #’s 5 – 8 p. 89 #’s 9 – 12 p. 91 #’s 13 – 16 p. 97 #’s 17 - 20 p. 103 #’s 23 – 24 p. 86 #’s 1, 3 – 6 p. 94 #’s 1 - 7 p. 106 #’s 1 - 3, 6, 7 p. 107 – 109 #’s 5 – 23, 25

  8. Isotopes and Atomic Mass atomic number - the number of protons in an atom or ion mass number - the sum of the protons and neutrons in an atom isotope - atoms which have the same number of protons and electrons but different numbers of neutrons

  9. Isotopes and Atomic Mass eg.

  10. Isotopes and Atomic Mass

  11. Isotopes and Atomic Mass 11 % 79 % 10 % not all isotopes are created equal

  12. Isotopes and Atomic Mass

  13. Isotopes and Atomic Mass atomic mass unit (AMU - p.43) a unit used to describe the mass of individual atoms the symbol for the AMU is u 1 u is 1/12 of the mass of a carbon-12 atom

  14. Isotopes and Atomic Mass average atomic mass (AAM) the AAM is the weighted average of all the isotopes of an element (p. 45) p. 14 # 5 p. 45 #’s 1 – 4 p. 46 #’s 1 – 6 p. 75 #’s 9 - 12

  15. Finding % Abundance eg. Br has two naturally occurring isotopes. Br-79 has a mass of 78.92 u and Br-81 has a mass of 80.92 u. If the AAM of Br is 79.90 u, determine the percentage abundance of each isotope.

  16. Let x = fraction of Br-79 Let y = fraction of Br-81 x + y = 1 78.92x + 80.92y = 79.90 Finding % Abundance y = 1 - x

  17. x + y = 1 78.92x + 80.92y = 79.90

  18. Avogadro’s Number (p. 47) p. 48

  19. Avogadro’s Number The MOLE is a number used by chemists to count atoms The MOLE is the number of atoms contained in exactly 12 g of carbon-12. In honor of Amedeo Avogadro, the number of particles in 1 mol has been called Avogadro’s number.

  20. How big is Avogadro's number? An Avogadro's number of soft drink cans would cover the surface of the earth to a depth of over 200 miles. Avogadro's number of unpopped popcorn kernels spread across the USA, would cover the entire country to a depth of over 9 miles.

  21. 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. How big is Avogadro's number?

  22. Avogadro’s Number 1 mole = 6.02214199 x 1023 particles 1 mol = 6.022 x 1023 particles NA = 6.022 x 1023 particles/mol

  23. Avogadro’s Number

  24. Avogadro’s Number 5 mol 3.011 x 1024 atoms 0.01 mol 6.022 x 1021 atoms 7.72 mol 4.65 x 1024 atoms 0.0133 mol 8.01 x 1021 atoms

  25. Avogadro’s Number Formulas: N = n x NA n = # of moles N = # of particles (atoms, ions, molecules, or formula units) NA = Avogadro’s #

  26. How many moles are contained in the following? 2.56 x 1028 Pb atoms 7.19 x 1021 CO2 molecules Avogadro’s Number

  27. Avogadro’s Number eg. Calculate the number of moles in 4.98 x 1025 atoms of Al. eg. How many formula units of Na2SO4 are in 5.69 mol of Na2SO4? # of Na ions? # of Oxygen atoms?

  28. Avogadro’s Number 1. How many molecules of glucose are in 0.435 mol of C6H12O6? How many carbon atoms? 2. Calculate the number of moles in a sample of glucose that has 3.56 x 1022 hydrogen atoms.

  29. Avogadro’s Number pp. 51 – 53: #’s 5 – 15 p. 54:  #’s 4 - 8

  30. Molar Mass The mass of one mole of a substance is called the molar mass of the substance eg. 1 mole of Pb has a mass of 207.19 g 1 mole of Ag has a mass of 107.87 g

  31. Molar Mass The symbol for molar mass is M and the unit is g/mol eg. MPb = 207.19 g/mol MAg = 107.87 g/mol

  32. Molar Mass The molar mass of a compound is the sum of the molar masses of the elements in the compound eg. Calculate the molar mass of: a) H2O b) C6H12O6 c) Ca(OH)2

  33. Molar Mass H2O has 2 hydrogens and 1 oxygen 2 x 1.01 = 2.02 1 X 16.00 = 16.00 18.02 g/mol

  34. Molar Mass C6H12O6 6 x 12.01 = 72.06 12 x 1.01 = 12.12 6 x 16.00 = 96.00 180.18 g/mol

  35. Molar Mass Ca(OH)2 1 x 40.08 = 40.08 2 x 16.00 = 32.00 2 x 1.01 = 2.02 74.10 g/mol Your calculator may not show the zeroes. There should be 2 digits after the decimal when adding molar masses

  36. Molar Mass p. 57: #’s 16 – 19 & Molar Masses Handout 1. 151.92 g/mol 7. 58.44 g/mol 2. 120.38 g/mol 8. 100.09 g/mol 3. 105.99 g/mol 9. 44.02 g/mol 4. 100.40 g/mol 10. 248.22 g/mol 5. 74.44 g/mol 11. 115.04 g/mol 6. 78.01 g/mol

  37. Molar Mass Calculations mass Avogadro’s # molar mass N = n x NA m = n x M

  38. Molar Mass Calculations m = n x M N = n x NA

  39. Molar Mass Calculations eg. How many moles are in 25.3 g of NO2? m = 25.3 g MNO2 = 46.01 g/mol

  40. Molar Mass Calculations eg. What is the mass of 4.69 mol of water? n = 4.69 mol Mwater = 18.02 g/mol m = n x M = (4.69 mol)(18.02 g/mol) = 84.5 g

  41. Molar Mass Calculations Practice: p. 59 #’s 20 - 23 p. 60 #’s 24 - 27

  42. The Mole #4 answers 1.a) 0.038 mol 2.a) 17.4 g 3.a) 5631 g b) 3.75 mol b) 1560. g b) 3.73 g c) 0.276 mol c) 528 g c) 10.02 g d) 23 mol d) 97513 g d) 1662.9 g e) 0.0575 mol e) 9328 g e) 981.2 g 4.a) 1.82 mol c) 0.02133 mol e) 0.0000573 mol b) 13 mol d) 4.3423 mol

  43. eg. How many molecules are in 26.9 g of water? m = 26.9 g Mwater= 18.02 g/mol NA = 6.022 x 1023 molecules/mol Find N Particle–Mole-Mass Conversions

  44. Particle–Mole-Mass Conversions N = n x NA = 1.493 X 6.022 x 1023 = 8.99 x 1023 molecules = 1.493 mol H2O

  45. eg. A sample of Sn contains 4.69 x 1028 atoms. Calculate its mass. N = 4.69 x 1028 NA = 6.022 x 1023 molecules/mol MSn = 118.69 g/mol Find m Particle–Mole-Mass Conversions

  46. Particle–Mole-Mass Conversions m = n x M = 77881 mol x 118.69 g/mol = 9.24 x 10 6 g = 77,881 mol

  47. Particle–Mole-Mass Conversions • Calculate the mass of 4.80 x 1024 water • molecules. • How many grams are in 2.53 x 1026 CH4 • molecules? • How many atoms are in 68.0 g of Sn? • Calculate the number of molecules • in 105 g of C6H12O6.

  48. Particle–Mole-Mass Conversions

  49. Particle–Mole-Mass Conversions

  50. Particle–Mole-Mass Conversions