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More Stoichiometry Problems involving Volume or Particles or Energy. Chapter 9 Section 1, pages 308 – 311. Stoichiometry Strategy. All problems involve three basic steps: Get to moles of ‘given’ Use the stoichiometric ratio Get out of moles of ‘find’. coeff . find coeff . given.
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More StoichiometryProblems involving Volume or Particles or Energy Chapter 9 Section 1, pages 308 – 311
Stoichiometry Strategy • All problems involve three basic steps: • Get to moles of ‘given’ • Use the stoichiometric ratio • Get out of moles of ‘find’ coeff. find coeff. given molfind molgiven Unitsgiven Unitsfind Which means we just need to figure out how to convert between moles and units of measure.
Gas Volume Problems (Using Molar Volume: 22.4 L/mol) Example: • What volume of NH3forms when 672 mLH2completely reacts? N2 (g) + 3 H2 (g) 2 NH3 (g) coeff. find coeff. given molfind molgiven √ Volfind Volgiven
Gas Volume Problems (Using Molar Volume: 22.4 L/mol) N2 (g) + 3 H2 (g) 2 NH3 (g) • Step 1 – get to moles of ‘given’ (note that volume must be converted to liters) 672 mLH2 0.0300 mol H2 1 L 1000 mL 1 mol H2 22.4 L √ coeff. find coeff. given molfind molgiven √ Volgiven Volfind
Gas Volume Problems (Using Molar Volume: 22.4 L/mol) N2 (g) + 3 H2 (g) 2 NH3 (g) • Step 2 – Use the stoichiometric ratio: 0.0300 mol H2 2 mol NH3 3 mol H2 0.0200 mol NH3 √ √ coeff. find coeff. given molfind molgiven √ Volfind Volgiven
Gas Volume Problems (Using Molar Volume: 22.4 L/mol) N2 (g) + 3 H2 (g) 2 NH3 (g) • Step 3 – get out of moles of ‘find’ • (This requires two conversions if you want the answer in milliliters): 0.0200 mol NH3 22.4 L NH3 1 mol NH3 1000 ml 1 L 448 mLNH3 √ √ coeff. find coeff. given molfind molgiven √ √ Volgiven Volfind
Gas Volume Problems (Using Molar Volume: 22.4 L/mol) Putting all steps together we have: 672 mLH2 1 L 1000 mL 1 mol H2 22.4 L H2 2 mol NH3 3 mol H2 22.4 L NH3 1 mol NH3 1000 ml 1 L 448 mLNH3 2 coeff. find coeff. given 1 molfind molgiven x molar volume 3 molar volume VolL of given VolL of find
Particle Stoichiometry Problems Example: • How many molecules of C5H8 form from 1.89 x 1024 molecules C5H12? C5H12 (l) C5H8 (l) + 2 H2 (g) coeff. find coeff. given molfind molgiven √ moleculesfind moleculesgiven
Particle Stoichiometry Problems C5H12 (l) C5H8 (l) + 2 H2 (g) • Step 1 – get to moles of given: 1.89 x 1024 molecules C5H12 1 mol 6.022 x 1023 3.14 mol C5H12 √ coeff. find coeff. given molfind molgiven Avogadro’s number √ moleculesfind moleculesgiven
Particle Stoichiometry Problems C5H12 (l) C5H8 (l) + 2 H2 (g) • Step 2 – Use the stoichiometric ratio: 3.14 mol C5H12 1 mol C5H8 1 mol C5H12 3.14 mol C5H8 √ √ coeff. find coeff. given molfind molgiven √ moleculesfind moleculesgiven
Particle Stoichiometry Problems C5H12 (l) C5H8 (l) + 2 H2 (g) • Step 3 – get out of moles of ‘find’: 3.14 mol C5H8 6.022 x 1023 1 mol C5H8 1.89 x 1024 molecules C5H8 √ √ coeff. find coeff. given molfind molgiven x Avogadro’s number √ √ moleculesgiven moleculesfind
Particle Stoichiometry Problems Putting all steps together we have: 1.89 x 1024 molecules C5H12 1 mol 6.022 x 1023 1 mol C5H8 1 mol C5H12 6.022 x 1023 1 mol C5H8 1.89 x 1024 molecules C5H8 coeff. find coeff. given 2 3 molfind molgiven 1 x Avogadro’s number Avogadro’s number moleculesgiven moleculesfind
particlesgiven particlesfind 6.022 x 1023 X 6.022 x 1023 Coefficient Find Coefficient Given molesgiven molesfind molar mass X molar mass gramsgiven gramsfind molar volume X molar volume volumeL of given volumeL of find The Mole Road