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Using Chemical Formulas

Using Chemical Formulas. 7-3. Beaker Breaker. Name the following compounds: CaCl 2 = ____________ P 3 O 6 = _____________ FeCl 2 =______________ H 2 SO 4 =______________. Formula Masses. sum of the average atomic masses of all the atoms represented in a formula

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Using Chemical Formulas

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  1. Using Chemical Formulas 7-3

  2. Beaker Breaker • Name the following compounds: CaCl2 = ____________ P3O6 = _____________ FeCl2 =______________ H2SO4 =______________

  3. Formula Masses • sum of the average atomic masses of all the atoms represented in a formula • (can be of a molecule, formula unit or ion) • Formula mass of H2O: • 2 (ave. atomic mass of H) +1(ave. at. mass of O) • = 2(1.01 amu) + 1(16.00 amu) • = 2.02 amu + 16.00 amu • = 18.02 amu

  4. Calculate the formula mass of the following: • sulfuric acid • calcium nitrate • phosphate ion • magnesium chloride

  5. sulfuric acid • 98.09 amu H2SO4 • calcium nitrate • 164.10 amu Ca(NO3)2 • phosphate ion • 94.97 amu PO43- • magnesium chloride • 95.21 amu MgCl2

  6. Molar Masses • sum of the masses of the elements present in a mole of the molecules or formula units that make up a compound • Molar mass of water, H2O: • 1 mole H2O = 2 mol H + 1 mol O • 2 mol H x 1.01 g H = 2.02 g H 1 mol H • 1 mol O x 16.00 g = 16.00 g O 1 mol O 18.02 g • Molar mass of water = 18.02 g/mol

  7. What is the molar mass of… • aluminum sulfide • sodium nitrate • barium hydroxide

  8. What is the molar mass of… • aluminum sulfide • Al2S3 150.17 g/mol • sodium nitrate • NaNO3 85.00 g/mol • barium hydroxide • Ba(OH)2 171.35 g/mol

  9. Beaker Breaker • Name the following the compounds: CaBr2 =_______________ H3PO3 =_______________ C3I7 =_________________ CuCl3 = _______________

  10. Using Molar Mass as a conversion factor between “moles” ↔ “mass” • What is the mass, in grams, of 0.50000 moles of barium hydroxide? • Given: 0.500000 mol Ba(OH)2 • Find: g Ba(OH)2 • Know: 1 mol Ba(OH)2 =171.35 g Ba(OH)2 • 0.500000 mol Ba(OH)2 x 171.35 g Ba(OH)2 1 mole Ba(OH)2 • = 85.675 g Ba(OH)2

  11. How many moles are in 6.60 g of ammonium sulfate? • Given: 6.60g (NH4)2SO4 • Find: 0.0499 mol (NH4)2SO4 • Know:1 mol(NH4)2SO4 = 132.17 g (NH4)2SO4 • (NH4)2SO4 = 2(N) + 8(H) + 1(S) + 4(O) • = 2(14.01) + 8(1.01) + 1(32.07) + 4(16.00) • 132.17 g/mol • 6.60g (NH4)2SO4 x 1 mol(NH4)2SO4 132.17 g (NH4)2SO4 • = 0.0499 mol (NH4)2SO4(4.99 x 10-2mol)

  12. Remember…. 1 mole = 6.02 x 1023 “things” • How many molecules are in 50.0 g of water? • Given: 50.0 g H2O • Find: molecules H2O • Know: 1 mol H2O = 18.02g • 1 mol H2O = 6.02 x 1023 molecules H2O • 50.0 g H2O x 1 mol H2O x 6.02 x 1023 molecules 18.02 g H2O 1 mol H2O • = 1.67 x 1024 molecules H2O

  13. White Board Practice with PartnersHow many moles of compound are there in the followinga. 6.60g (NH4)2SO4b. 4,500g Ca(OH)2

  14. Answers • A. 0.0500mol • B. 61mol

  15. White Board Practice with Partners • How many molecules are there in the following: a. 25.0g H2SO4 b. 125g of C12H22O11

  16. Answers • A. 1.53 x1023 molecules • B. 2.20 x1023 molecules

  17. Beaker Breaker • Write the formulas of the following compounds • Nitric Acid =___________ • Hydroiodic acid =____________ • Magnesium Fluoride =____________ • Tetracarbon nonahydride =__________

  18. Percentage Composition • % = part x 100 whole • percentage by mass of each element in a cmpd

  19. Find the % copper in copper(I) sulfide • % Cu = part Cu x 100 whole Cu2S • % Cu = mass of Cu in 1 mole of Cu2S x 100 mass of 1 mol of Cu2S Or...% Cu= mass of Cu in 1 mole of Cu2S x 100 molar mass of Cu2S • Cu2S = 159.17 g/mol (molar mass..on bottom) • 1 mol Cu2S, there are 2 mol Cu = 127.10 g Cu (top term)

  20. Find the % copper in copper(I) sulfide Know: • % Cu = mass of Cu in 1 mole of Cu2S x 100 mass of 1 mol of Cu2S • 1 mol of Cu2S = 159.17 g Cu2S • 1 mol of Cu2S= 2mol Cu = 2(63.546g)= 127.10g • = 127.10 g Cu x 100 159.17 g Cu2S • = 79.852% Cu in Cu2S

  21. What is the percent carbon in ammonium carbonate? Know: (NH4)2CO3 • % C = grams of C in 1 mol (NH4)2CO3x 100 molar mass of (NH4)2CO3 • 1 mol (NH4)2CO3 = 1 mol C = 12.01 g C • 1 mol (NH4)2CO3 = 96.11 g (NH4)2CO3 • = 12.01 g C x 100 96.11 g • = 12.50% C

  22. Beaker Breaker • Phosphoric acid can be used in orthodontics to roughen the surface of teeth before the placement of braces. Write the chemical formula for phosphoric acid. • Explain your method used to arrive to that answer.

  23. Homework CheckPg 236 #25 a. NH41+ Ammonium b.ClO3- Chlorate c. OH- Hydroxide d.SO42- Sulfate e. NO3- Nitrate f.CO32- Carbonate g. PO43- Phosphate h. CH3COO- Acetate i. HCO3- Bicarbonate j. CrO42- Chromate

  24. Mix Review Challenge Write the name or formula of the following: • MgSO3 =______________ • Sodium Hydroxide = __________ • Nickel (II) Fluoride =___________ • P2H3 =__________

  25. Answers • Magnesium Sulfite • NaOH • NiF2 • Diphosphorus Trihydride

  26. Mix Review Challenge • Write the name or formula of the following: 5. Sulfurous acid =___________ 6. Copper (II) Chloride =_________ 7. AlPO4 =____________ 8. TetraSulfur Heptoxide =__________

  27. Answers 5. H2SO3 6. CuCl2 7. Aluminum Phosphate 8. S4O7

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