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Modern Chemistry Chapter 9 Stoichiometry

Modern Chemistry Chapter 9 Stoichiometry. Modern Chemistry Chapter 9 Stoichiometry. composition stoichiometry deals with the mass relationships of elements in compounds. reaction stoichiometry involves the mass relationships between reactants and products in a chemical reaction.

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Modern Chemistry Chapter 9 Stoichiometry

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  1. Modern Chemistry Chapter 9Stoichiometry

  2. Modern Chemistry Chapter 9Stoichiometry • composition stoichiometry deals with the mass relationships of elements in compounds. • reaction stoichiometry involves the mass relationships between reactants and products in a chemical reaction.

  3. Types of Stoichiometry Problems • mole to mole(Both the given and the unknown quantities are amounts in moles.) • mole to mass (The given amount is in moles and the unknown amount is in grams.) • mass to mole(The given amount is in grams and the unknown amount is in moles.) • mass to mass (Both the given and the unknown amount is in grams.)

  4. mole ratio- A conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction. Found by using the coefficients in the balanced formula equation of the reaction. molar mass- Equal to the mass in grams of one mole of an element or a compound. Found by adding the individual element atomic masses from the formula of the compound. Mole Ratio & Molar Mass

  5. Section Review Problems • Do section review problems #1 through #4 on page 301 of the textbook.

  6. Section Review page 301 1- The branch of chemistry that deals with mass relationships in compounds and in chemical reactions. 2 HgO 2 Hg + O2 2- a) 2 mol HgO & 2 mol HgO 2 mol Hg 1 mol O2 2 mol Hg & 2 mol Hg 2 mol HgO 1 mol O2 1 mol O2 & 1 mol O2 2 mol HgO 2 mol Hg

  7. Section Review page 301 3- It is used to convert moles of one substance into moles of another substance. 4- The formula equation MUST be BALANCED so mole ratios can be determined.

  8. Using Conversion Factors Amount coefficient amount of of given x of unknown = unknown substance coefficient substance in moles of known in moles # moles x mole ratio = #moles of given unknown Do practice problems #1 & #2 on page 306 of text.

  9. Page 306 #1 3 H2 + N2 2 NH3 6 mol H2 x 2 mol NH3 = 4mol NH3 3m mol H2

  10. Page 306 #2 2 KClO3 2 KCl + 3 O2 15 mol O2 x 2 mol KClO3= 10 mol KClO3 3 mol O2

  11. Chapter 9 quiz #1- mole to mole calculations 6 NaBr + Mg3(PO4)2 2 Na3PO4 + 3 MgBr2 Use the above balanced formula equation to solve the following: 1- 7.0 moles of NaBr will produce ? moles Na3PO4 2- 3.0 moles of Mg3(PO4)2 will yield ? moles MgBr2 3- 0.5 moles of NaBr will react with ? moles Mg3(PO4)2 4- 2.5 moles of NaBr will yield ? moles Na3PO4 5- 2.5 moles NaBr will produce ? moles MgBr2

  12. Using Conversion Factors amount of mass in given x moles unknown x molar = grams of substance moles known mass of unknown in moles unknown substance # moles x mole x molar = mass of unknown given ratio mass (in grams) unknown Do practice problems #1 & #2 on page 308 of the textbook.

  13. Page 308 #1 & 2 2 Mg + O2 2 MgO 2.00 mol Mg x 2 mol MgO x 40.3 g MgO = 80.6 g MgO 2 mol Mg 1 mol MgO 6 CO2 + 6 H2O  C6H12O6 = 6 O2 10 mol CO2 x 1 mol C6H12O6 x 180 g C6H12O6 = 300 g C6H12O6 6 mol CO2 1 mol C6H12O6

  14. Chapter 9 Quiz #2- mole-mass problems 3 MgF2 + Al2O3 3 MgO + 2 AlF3 Use the above balanced formula equation to answer the following questions. 1- 2.0 mol MgF2 will yield ? grams of MgO 2- 4.0 mol of Al2O3  ? grams of AlF3 3- If 6.0 mol of MgO is produced, ? grams of AlF3 4- 0.6 mol MgF2  ? grams of AlF3 5- 2.75 mol Al2O3  ? grams of MgO

  15. Using Conversion Factors mass (g)x 1 mol given x mol unknown = moles of of given molar mass mol given unknown substance of given substance grams x 1 x mole ratio = moles unknown molar mass Do practice problems #1 & #2 on page 309 of the textbook.

  16. Practice problems page 309 2 HgO 2 Hg + O2 125 g O2 x 1 mol O2 x 2 mol HgO = 7.81 mol HgO 32 g O2 1 mol O2 125 g O2 x 1 mol O2 x 2 mol Hg = 7.81 mol Hg 32 g O2 1 mol O2

  17. chapter 9 quiz #3- mass-mole problems Na2O + CaF2 2 NaF + CaO Use the above equation to solve the problems. 1- 156.1 grams of CaF2  ? mol CaO 2- 186 g Na2O  ? mol NaF 3- 31 g Na2O  ? mol CaO 4- 31 g Na2O  ? mol NaF 5- A yield of 84 g NaF  ? mol CaO

  18. Chemistry Chapter 9- Stoichiometry Practice Problems 2 NaF + CaO Na2O + CaF2 1- 4.5 moles of NaF will produce -?- moles of Na2O ? 4.5 mol NaF x 1 mol Na2O/2 mol NaF = 2.25 moles Na2O 2- 3.2 moles of CaO will produce -?- grams of CaF2 ? 3.2 mol CaO x 1 mol CaF2/1 mol CaO x 78.1 g CaF2/mol CaF2 = 249.9 g CaF2

  19. 2 NaF + CaO Na2O + CaF2 3- 168.0 grams of NaF will produce -?- moles of Na2O ? 168.0 /42.0 x 1 /2 = 2.0 mol Na2O 4- 112.2 grams of CaO will produce -?- moles of CaF2 ? 112.2/56.1 x 1/1 = 2.0 mol CaF2

  20. 5- Calculate the molar mass of each of the reactants & products of the above balanced formula equation. Use the molar masses in the following problems. a- AlN = (1 x 27.0) + (1 x 14.0) = 41.0 g/mol b- Na2O = (2 x 23.0) + (1 x 16.0) = 62.0 g/mol c- Al2O3 = (2 x 27.0) + (3 x 16.0) = 102.0 g/mol d- Na3N = (3 x 23.0) + (1 x 14.0) = 83.0 g/mol

  21. 2 AlN + 3 Na2O  Al2O3 + 2 Na3N 6- 82.0 grams of AlN will produce -?- moles of Al2O3 ? 82.0/41.0 x 1/2 = 1.0 mol Al2O3 7- 164.0 grams AlN will produce -?- moles of Na3N ? 164.0/41.0 x 2/2 = 4.0 mol Na3N

  22. 2 AlN + 3 Na2O  Al2O3 + 2 Na3N 8- 2.5 moles of Na2O will produce -?- grams of Na3N ? 2.5 x 2/3 x 83.0 = 138.3 g Na3N 9- 0.75 moles of Na2O will produce -?- moles of Al2O3 ? 0.75 x 1/3 = 0.25 mol Al2O3 10- 11.0 moles of Na2O will produce -?- grams of Na3N ? 11.0 x 2/3 x 83.0 = 608.7 g Na3N

  23. 2 H2 + O2 2 H2O 11- 8.0 grams of H2 will react with -?- moles of O2 ? 8.0/2.0 x 1/2 = 2.0 mol O2 12- 64.0 grams of O2 will produce -?- moles of H2O ? 64.0/32.0 x 2/1 = 4.0 mol H2O 13- 0.25 moles of H2 will produce -?- moles of H2O ? 0.25 x 2/2 = 0.25 mol H2O

  24. 2 H2 + O2 2 H2O 14- 1.5 moles of H2 will produce -?- grams of H2O ? 1.5 x 2/2 x 18.0 = 27.0 g H2O 15- 14 moles of O2 will produce -?- moles of H2O ? 14 x 2/1 = 28.0 mol H2O

  25. Using Conversion Factors mass (g) x 1 mol given x mol unknown x molar mass unknown = mass of given molar mass mol given 1 mol unknown of un- substance of given known grams x 1 x mole ratio x molar mass = mass of unknown given molar mass Do practice problems #1, #2, & #3 on page 311 of textbook. Do section review problems #1 - #5 on page 311 of textbook.

  26. Practice problems page 311 NH4NO3 N2O + 2 H2O 32 g N2O x 1 mol N2O x 1 mol NH4NO3 x 80 g NH4NO3 = 60 g NH4NO3 44 g N2O 1 mol N2O 1 mol NH4NO3

  27. Chapter 9 quiz #4- mass-mass problems Na2O + CaF2 2 NaF + CaO 1- 124 g Na2O  ? grams NaF 2- 124 g Na2O  ? grams CaO 3- 234.3 g CaF2  ? g NaF 4- 234.3 g CaF2  ? g CaO 5- 84.0 g NaF  ? g CaO

  28. The “MOLE HILL” x mole ratio # moles known # moles unknown ÷ molar mass x molar mass of known of unknown mass of known mass of unknown

  29. Stoichiometry Practice Problems 2 H2 + O2 2 H2O 1) 2.5 mol H2 x 1 mol O2 = 1.25 mol O2 2 mol H2 2) 2.5 mol H2 x 2 mol H2O = 2.5 mol H2O 2 mol H2 3) 2.5 mol H2 x 1 mol O2 x 32 g O2 = 40 g O2 2 mol H2 1 mol O2 4) 2.5 mol H2 x 2 mol H2O x 18 g H2O = 45 g H2O 2 mol H2 1 mol H2O

  30. Stoichiometry Practice Problems 2 H2 + O2 2 H2O 5) 16 g H2 x 1 mol H2 x 1 mol O2 = 4.0 mol O2 2 g H2 2 mol H2 6) 16 g H2 x 1 mol H2 x 2 mol H2O = 8.0 mol H2O 2.0 g H2 2 mol H2 7) 16 g H2 x 1 mol H2 x 1 mol O2 x 32 g O2= 128 g O2 2.0 g H2 2 mol H2 1 mol O2 8) 16 g H2 x 1 mol H2 x 2 mol H2O x 18 g H2O = 144 g H2O 2.0 g H2 2 mol H2 1 mol H2O

  31. Limiting Reactant & Percentage Yield • limiting reactant is the reactant that limits the amount of the other reactant that can combine and the amount of product that can be formed in a chemical reaction. • excess reactantis the substance that is NOT completely used up in a chemical reaction.

  32. Sample & Practice Problems See sample problem F on page 313 of textbook. Do practice problems #1 on page 313. See sample problem G on pages 314-315. Do practice problems #1 & #2 on page 315.

  33. QuickLAB • Do the QuickLAB titled “Limiting Reactants in a Recipe” on page 316 of the textbook. Yes, cooking IS chemistry!

  34. Percentage Yield • theoretical yield is the maximum amount of product that can be produced from a given amount of reactant • actual yield of a product is the measured amount of a product obtained from a reaction • percentage yieldis the ratio of the actual yield to the theoretical yield multiplied by 100 • percentage yield = actual yield x 100 theoretical yield

  35. Problems • see sample problem H on pages 317-318 of textbook • Do practice problems #1 & #2 on page 318. • Do section review problems #1 - #4 on page 318. • Do critical thinking problems #37, #38, #39, & #40 on pages 322 & 323.

  36. Chapter 9 test review • 20 multiple choice questions • definitions of composition & reaction stoichiometry • mole ratios: their definition & use • SI units of molar mass • identify mole ratio from balanced formula equation • 5 mole-mole problems • Definitions & practical applications of excess reactant & limiting reactant • definitions & practical applications of theoretical yield, actual yield, & % yield

  37. Honors Chemistry Chapter 9 Test Review • 25 multiple choice • Know the definitions of reaction & composition stoichiometry, mole ratio, and units of molar mass. • Know what mole ratio means and how it is used in stoichiometry. • Determine mole ratio using balanced formula equation. (2) • Perform mole to mole stoichiometric calculations (4). • Perform mole to mass stoichiometric calculations (1). • Perform mass to mole stoichiometric calculations (1). • Perform mass to mass stoichiometric calculations (1). • Know definitions and applications of limiting and excess reactants. • Know the definitions & applications of actual yield, theoretical yield, and percent yield.

  38. Practice #2 2 Na3PO4 + 3 CaSO4 3 Na2SO4 + Ca3(PO4)2 Known = 3 moles CaSO4 unknown = ? Moles Na3PO4 3 x 2/3 = 2 moles Na3PO4 Known = 2.0 moles Na3PO4 unknown = ? Moles Na2SO4 2 x 3/2 = 3 moles Na2SO4 Known = 1.5 moles Ca3(PO4)2 unknown = ? Moles CaSO4 1.5 x 3/1 = 4.5 moles CaSO4 Known = 4.4 moles CaSO4 unknown = ? Moles Na3PO4 4.4 x 2/3 = 2.9 moles Na3PO4

  39. 2 Na3PO4 + 3 CaSO4 3 Na2SO4 + Ca3(PO4)2 Known = 6.0 moles Na3PO4 unknown = ? Moles Na2SO4 6.0 x 3/2 = 9.0 moles Na2SO4 Known = 5.4 moles CaSO4 unknown = ? Moles Na3PO4 5.4 x 2/3 = 3.6 moles Na3PO4 Known = 0.6 moles Na3PO4 unknown = ? Moles CaSO4 0.6 x 3/2 = 0.9 moles CaSO4

  40. Stoichiometry Practice #3 4 Na3N + 3 O2 6 Na2O + 2 N2 Assume you have 12.0 moles of Na3N. How many moles of O2 do you need? How many moles of Na2O will you get? How many moles of N2 will you get?

  41. Stoichiometry Practice #3 4 Na3N + 3 O2 6 Na2O + 2 N2 Assume you have 12.0 moles of Na3N. How many moles of O2 do you need? 12 x 3/4 = 9 moles O2 How many moles of Na2O will you get? 12 x 6/4 = 18 moles Na2O How many moles of N2 will you get? 12 x 2/4 = 6 moles N2

  42. Practice #3 4 Na + O2 2 Na2O If you have 4 moles of Na, how many grams of O2 will you need? If you have 64 grams of O2, how many moles of Na2O will you produce? If you have 46 grams of Na, how many grams of O2 will you need?

  43. Practice #3 4 Na + O2 2 Na2O If you have 4 moles of Na, how many grams of O2 will you need? 4 x 1/4 x 32 = 32 grams O2 If you have 64 grams of O2, how many moles of Na2O will you produce? 64/32 x 2/1 = 4 moles Na2O If you have 46 grams of Na, how many grams of O2 will you need? 46/23 x 1/4 x 32 = 16 grams O2

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