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Chapter 4 Chemical Quantities and Aqueous Reactions 77 (b) Skeletal reaction: C₃H₆(₈) + O₂(₈) + Balance C: C₃H₆(₈) + O₂(₈) + Balance H: C₃H₆(₈) + + Balance O: + + Clear fraction: + + 6H₂O(g) (c) Skeletal reaction: Ca(s) + CaO(s) Balance O: Ca(s) + 2 CaO(s) Balance Ca: + (d) Skeletal reaction: C₅H₁₂S(l) + + + SO₂(g) Balance C: C₅H₁₂S(l) + O₂(₈) + + Balance H: + + 6H₂O(g) + Balance S: C₅H₁₂S(l) + + 6H₂O(g) + Balance O: + + + Cumulative Problems 4.101 Given: in 100 g solution, 20.0 g C₂H₆O₂; density of solution = 1.03 g/mL Find: M of solution Conceptual Plan: g C₂H₆O₂ mol C₂H₆O₂ and g solution mL solution L solution 1 mol C₂H₆O₂ 1.00 mL 1L 62.07 g C₂H₆O₂ 1.03 g 1000 mL then M C₂H₆O₂ mol C₂H₆O₂ M = L solution Solution: X 62.07 1 mol C₂H₆O₂ = 0.3222 mol C₂H₆O₂ 100.0 X 1.00 solution X 1000 1L mL = 0.09709 L 1.03 M = 0.3222 0.09709 mol C₂H₆O₂ L = 3.32 M Check: The units of the answer (M C₂H₆O₂) are correct. The magnitude of the answer is reasonable because the concentration of solutions is usually between 0 M and 18 M. 4.103 Given: 2.5 g Find: g Conceptual Plan: g mol NaHCO₃ mol HCI g HCI 1 mol 1 mol 36.46 g HCI 84.01 g 1 mol 1 mol Solution: HCl(aq) + NaHCO₃(aq) + + 2.5 1 X 1 1 X 36.46 1 HCI = 1.1 g Check: The units of the answer (g HCI) are correct. The magnitude of the answer is reasonable because the molar mass of HCI is less than the molar mass of NaHCO₃. 4.105 Given: 1.0 kg C₈H₁₈ Find: kg CO₂ Conceptual Plan: kg C₈H₁₈ g C₈H₁₈ mol C₈H₁₈ mol g kg CO₂ 1000 g 1 mol C₈H₁₈ 16 mol CO₂ 44.01 g CO₂ kg kg 114.22 g C₈H₁₈ 2 mol C₈H₁₈ 1 mol CO₂ 1000 g Solution: 2 + + 18 1.0 X 1000 X 114.22 1 mol X 2 16 mol mol X 44.01 1 mol kg = 3.1 kg CO₂ Check: The units of the answer (kg CO₂) are correct. The magnitude of the answer is reasonable because the mole ratio of CO₂ to C₈H₁₈ is 8:1. Copyright © 2017 Pearson Education, Inc.