Chem Unit5

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Chem Unit5

  1. 1. Back to Moles <ul><li>• number of atoms in exactly 12 grams carbon-12 </li></ul>
  2. 2. Avogadro’s Number <ul><li>There are 6.02 x 10 23 particles in a mole of any substance. </li></ul>
  3. 3. Molar Mass <ul><li>Mass of one MOLE of pure substance </li></ul><ul><li>Helium: 4.00 grams -------> 4 grams per mole </li></ul><ul><li>Lithium 6.94 grams ---------> 6.94 grams per mole </li></ul><ul><li>Mercury 200.59 grams -------> 200.59 grams per mole </li></ul>
  4. 4. 0.1 Moles of Uranium <ul><li>(0.1 moles) x 238 grams/mole </li></ul><ul><li>= 23.8 grams </li></ul>
  5. 5. 0.1 moles Uranium <ul><li>How many atoms? </li></ul><ul><li>6.022 x 10 23 atoms/mole x 0.1 moles </li></ul><ul><ul><ul><li>= 6.022 x 10 22 atoms </li></ul></ul></ul>
  6. 6. Molecules <ul><li>5 moles of CO 2 </li></ul><ul><li>= 5 moles x 6.022 x 10 23 molecules/mole </li></ul><ul><li>= 3.1 x 10 24 molecules of CO 2 </li></ul>
  7. 7. Molar Mass <ul><li>Mass in grams of one mole </li></ul><ul><li>of the substance </li></ul><ul><li>CO 2 : mass C + 2 (mass O) </li></ul><ul><li>= 12 + 2(16) = 44 grams </li></ul>
  8. 8. Mass -> Moles <ul><li>Converting from g to moles: </li></ul><ul><li>For 112 grams of C 2 H 4 : </li></ul>Grams of Substance Molar mass MOLES
  9. 9. Mass -> Moles <ul><li>Converting from g to moles: </li></ul><ul><li>For 112 grams of C 2 H 4 : </li></ul><ul><li>112 g x 1 mole/28 g = 4 moles </li></ul>Grams of Substance Molar mass MOLES
  10. 10. Moles -> Molecules <ul><li>Converting from moles to Molecules </li></ul><ul><li>For 4 moles of C 2 H 4 : </li></ul><ul><li>4 moles x 6.02 x 10 23 molecules/mole = 2.41 x 10 24 molecules </li></ul>Moles Avogadro’s Number molecules
  11. 11. Law of Definite Proportions <ul><li>Joseph Proust </li></ul><ul><li>Regardless of the source, a </li></ul><ul><li>compound always has the </li></ul><ul><li>same proportion of elements </li></ul>
  12. 12. Law of Definite Proportions <ul><li>Copper (II) Carbonate </li></ul>CuCO 3 -> Copper + Carbon + Oxygen 51.36% 9.72% 38.85%
  13. 13. Percent Composition <ul><li>CO CO 2 </li></ul><ul><ul><li>28 g/mole 44 g/mole </li></ul></ul><ul><ul><li>C: 12/28 = 42.86% C: 12/44 = 27.27% </li></ul></ul><ul><ul><li>O: 16/28 = 57.14% O: 32/44 = 72.73% </li></ul></ul><ul><ul><li>Two different compound with different percent </li></ul></ul><ul><ul><li>compositions and different properties </li></ul></ul>
  14. 14. Empirical Formula <ul><li>Smallest whole number ratio of atoms in a compound </li></ul><ul><li>Caffeine </li></ul><ul><li>Molecular formula C 8 H 10 N 4 O 2 </li></ul><ul><li>Empirical formula C 4 H 5 N 2 O </li></ul>
  15. 15. Percent Composition -> Empirical Formula <ul><li>Vinegar </li></ul><ul><li>C: 40% H: 6.67% </li></ul><ul><li>O: 53.33% </li></ul>
  16. 16. Percent Composition -> Empirical Formula <ul><li>Vinegar assume 100 g </li></ul><ul><li>C: 40 grams H: 6.67 grams </li></ul><ul><li>O: 53.33 grams </li></ul>
  17. 17. Percent Composition -> Empirical Formula <ul><li>C: 40 g x 1mole/12g = 3.33 moles H: 6.67 g x 1 mole/1g = 6.67 moles </li></ul><ul><li>O: 53.33 g x 1 mole/16 g = 3.33 moles </li></ul>
  18. 18. Percent Composition -> Empirical Formula <ul><li>C: 40 g x 1mole/12g = 3.33 moles H: 6.67 g x 1 mole/1g = 6.67 moles </li></ul><ul><li>O: 53.33 g x 1 mole/16 g = 3.33 moles </li></ul><ul><li>Empirical Formula: CH 2 O </li></ul>
  19. 19. Percent Composition -> Empirical Formula <ul><li>C: 40 g x 1mole/12g = 3.33 moles H: 6.67 g x 1 mole/1g = 6.67 moles </li></ul><ul><li>O: 53.33 g x 1 mole/16 g = 3.33 moles </li></ul><ul><li>Actual Formula: C 2 H 4 O 2 </li></ul>
  20. 20. Percent Composition -> Empirical Formula <ul><li>C: 40 g x 1mole/12g = 3.33 moles H: 6.67 g x 1 mole/1g = 6.67 moles </li></ul><ul><li>O: 53.33 g x 1 mole/16 g = 3.33 moles </li></ul><ul><li>Actual Formula: C 2 H 4 O 2 </li></ul>
  21. 21. Empirical Formula-> Molecular Formula <ul><li>Empirical Formula: CH 2 O </li></ul><ul><li>Molecular Formula: C 2 H 4 O 2 </li></ul><ul><li>Molecular Formula is a whole number multiple of empirical formula </li></ul>
  22. 22. Empirical Formula-> Molecular Formula <ul><li> Butyric Acid = butter flavor </li></ul><ul><li>Empirical formula = C 2 H 4 O </li></ul><ul><li>Molar mass = 88 g/mole </li></ul><ul><li>Molecular formula = </li></ul>
  23. 23. Empirical Formula-> Molecular Formula <ul><li> Butyric Acid = butter flavor </li></ul><ul><li>Empirical formula = C 2 H 4 O </li></ul><ul><li>Molar mass = 88 g/mole </li></ul><ul><li>Mass of emp. formula = 44 </li></ul><ul><li>Molecular formula = </li></ul>
  24. 24. Empirical Formula-> Molecular Formula <ul><li> Butyric Acid = butter flavor </li></ul><ul><li>Empirical formula = C 2 H 4 O </li></ul><ul><li>Molar mass = 88 g/mole </li></ul><ul><li>Mass of emp. formula = 44 </li></ul><ul><li>Molecular formula = C 4 H 8 O 2 </li></ul>
  25. 25. Formula -> Percent Composition <ul><li>Empirical formula </li></ul><ul><li> Butyric Acid: C 2 H 4 O Molar mass C x 2 = 12 x 2 = 24 </li></ul><ul><li>Molar mass H x 4 = 1 x 4 = 4 </li></ul><ul><li>Molar mass O = 16 44 g/mole </li></ul>
  26. 26. Formula -> Percent Composition <ul><li>Empirical formula </li></ul><ul><li> Butyric Acid: C 2 H 4 O C = 24/44 = 0.545 = 54.5% H = 4/44 = 0.091 = 9.1% </li></ul><ul><li>O = 16/44 = 0.364 = 36.4% </li></ul>
  27. 27. Chemical VS. Physical Change <ul><li>Physical Chemical </li></ul>
  28. 28. Chemical VS. Physical Change <ul><li>Physical Chemical • change in phase • atomic rearrangement </li></ul><ul><li>• change in appearance, • energy change </li></ul><ul><li>shape (absorption or release) </li></ul>
  29. 29. Chemical Equations <ul><li>Shorthand symbols: </li></ul><ul><li>(s), (l), (g) = solid, liquid, gas phases </li></ul><ul><li>(aq) = substance in aqueous solution </li></ul><ul><li>--> = reaction event AX -> BY </li></ul><ul><li><=> reaction in equilibrium (reversible) </li></ul>
  30. 30. Chemical Equations <ul><li>Silicon tetrachloride and water react to form silicon dioxide and hydrochloric acid </li></ul>
  31. 31. Chemical Equations <ul><li>Silicon tetrachloride and water react to form silicon dioxide and hydrochloric acid </li></ul>SiCl 4 + H 2 O SiO 2 + HCl Reactants Products
  32. 32. Chemical Equations <ul><li>Silicon tetrachloride and water react to form silicon dioxide and hydrochloric acid </li></ul>SiCl 4 + 2 H 2 O SiO 2 + 4 HCl Balanced
  33. 33. Balancing Chemical Equations <ul><li>Conservation of Matter: </li></ul><ul><li> H 2 + O 2 ---------------> H 2 O </li></ul>
  34. 34. Balancing Chemical Equations <ul><li>Conservation of Matter: </li></ul><ul><li> 2 H 2 + O 2 ---------------> 2 H 2 O </li></ul>
  35. 35. Balancing Chemical Equations <ul><li>propane gas + oxygen gas -> carbon dioxide gas + water vapor </li></ul>
  36. 36. Balancing Chemical Equations <ul><li>propane gas + oxygen gas -> carbon dioxide gas + water vapor </li></ul><ul><li> C 3 H 8 (g) O 2(g) -> CO 2(g) H 2 O(g) </li></ul>
  37. 37. Balancing Chemical Equations <ul><li>propane gas + oxygen gas -> carbon dioxide gas + water vapor </li></ul><ul><li> C 3 H 8 (g) O 2(g) -> 3 CO 2(g) H 2 O(g) </li></ul>
  38. 38. Balancing Chemical Equations <ul><li>propane gas + oxygen gas -> carbon dioxide gas + water vapor </li></ul><ul><li> C 3 H 8 (g) O 2(g) -> 3 CO 2(g) 4 H 2 O(g) </li></ul>
  39. 39. Balancing Chemical Equations <ul><li>RULES : </li></ul><ul><li>• Identify reactants and products </li></ul><ul><li>• Count atoms </li></ul><ul><li>• Insert coefficients </li></ul><ul><li>• Check your work </li></ul>
  40. 40. Balancing Chemical Equations <ul><li>aluminum metal and iron (II) nitrate react to form aluminum nitrate and iron metal </li></ul>
  41. 41. Balancing Chemical Equations <ul><li>aluminum metal and iron (II) nitrate react to form aluminum nitrate and iron metal </li></ul>Al + Fe(NO 3 ) 2 Al(NO 3 ) 3 + Fe
  42. 42. Balancing Chemical Equations <ul><li>aluminum metal and iron (II) nitrate react to form aluminum nitrate and iron metal </li></ul>2 Al + 3 Fe(NO 3 ) 2 2 Al(NO 3 ) 3 + 3 Fe Balanced
  43. 43. Types of Chemical Equations <ul><li>1. Combustion </li></ul><ul><li>2. Synthesis </li></ul><ul><li>3. Decomposition </li></ul><ul><li>4. Single Displacement </li></ul><ul><li>Double Displacement </li></ul><ul><li>Acid – Base* </li></ul>
  44. 44. Combustion Reaction of a carbon-based compound with oxygen 2 C 4 H 10 + 13 O 2 8 CO 2 + 10 H 2 O butane
  45. 45. Combustion Alcohol lamp C 2 H 5 OH + 3 O 2 2 CO 2 + 3 H 2 O
  46. 46. Synthesis Forming a single compound from two or more reactants H 2 + O 2 H 2 O
  47. 47. Synthesis Forming a single compound from two or more reactants 2 Na + Cl 2 2 NaCl
  48. 48. Decomposition Breakdown of a single compound (Opposite of synthesis) 2 NaN 3 2 Na + 3N 2
  49. 49. Decomposition Breakdown of a single compound (Opposite of synthesis) NH 4 NO 3 N 2 O + 2 H 2 O
  50. 50. Single Displacement A single element reacts with a Compound and displaces another element from that compound Zn + 2 HCl ZnCl 2 + H 2
  51. 51. Single Displacement A single element reacts with a Compound and displaces another element from that compound 2 K + 2 H 2 O 2 KOH + H 2
  52. 52. Activity Series Element Reactivity K Ca Na React with cold water and acids to replace hydrogen; react with oxygen to form oxides Mg Al Zn Fe React with steam (not cold water) and acids to replace hydrogen; react with oxygen to form oxides Ni Pb Do not react with water; react with acids to replace hydrogen; react with oxygen to form oxides H 2 Cu React with oxygen to form oxides Ag Au Unreactive; form oxides only indirectly
  53. 53. Activity Series <ul><li>What will happen if iron (steel wool) is added to a copper(II) sulfate solution? </li></ul>
  54. 54. Activity Series <ul><li>Fe (s) + CuSO 4 (aq) -> Cu (s) + FeSO 4(aq) </li></ul>
  55. 55. Double Displacement Two compounds exchange ions and Form new compounds Pb(NO 3 ) 2 + KI PbI 2(s) + 2 KNO 3
  56. 56. Net Ionic Equations When aqueous solutions are mixed, new ionic combinations are made. Mass and Charge must be conserved. Na 2 SO 4(aq) + Sr(NO 3 ) 2(aq) SrSO 4(s) + 2 NaNO 3(aq) precipitate
  57. 57. Net Ionic Equations Precipitate = insoluble solid that Separates from solution Na 2 SO 4(aq) + Sr(NO 3 ) 2(aq) SrSO 4(s) + 2 NaNO 3(aq) precipitate
  58. 58. Net Ionic Equations Na 2 SO 4 - > 2 Na + + SO 4 2- Sr(NO 3 ) 2 - > Sr 2+ + 2 NO 3 - NaNO 3 - > Na + + NO 3 - Na 2 SO 4(aq) + Sr(NO 3 ) 2(aq) SrSO 4(s) + 2 NaNO 3(aq) precipitate
  59. 59. Net Ionic Equations Na 2 SO 4 - > 2 Na + + SO 4 2- Sr(NO 3 ) 2 - > Sr 2+ + 2 NO 3 - NaNO 3 - > Na + + NO 3 - 2 Na + + SO 4 2- + Sr 2+ + 2 NO 3 - SrSO 4(s) + 2 Na + + 2 NO 3 - spectator ions precipitate
  60. 60. Solubility Rules All alkali metal and NH 4 + salts are soluble; All nitrates (NO 3 ) are soluble; All Halides (F, Cl, Br, I) are soluble except Ag + and Pb 2+ Sulfates(SO 4 ), except for Ca 2+ , Ba 2+ , Sr 2+ , Pb 2+ are soluble Carbonates (CO 3 ) are insoluble except for alkali metal and NH 4 .
  61. 61. Net Ionic Equations Li 2 CO 3 + BaBr 2 BaCO 3 + 2 LiBr
  62. 62. Net Ionic Equations Li 2 CO 3 -> 2 Li + + CO 3 2- BaBr 2 -> Ba 2+ + 2 Br - Li 2 CO 3 + BaBr 2 BaCO 3 + 2 LiBr precipitate
  63. 63. Unit 5 Review Molar Mass g <-> atoms/molecules <-> moles Percent Composition Empirical and Molecular Formula Chemical equations: Word Equations, Balancing

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