L26S07_BondEnergy 03-19-07 - Chem1A, L26: "Bond...

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Unformatted text preview: Chem1A, L26: "Bond Energies" Human Thermochemistry 1 Nutritional Calorie (Cal, C) = 1 kcal 1 calorie (cal,c) = 4.18 J 1 Watt (W) = 1 J/sec Nutrition: Daily caloric intake 100 W ~ 107 J/day ~ 2500 Cal/day. x 1 day 2000 University of California L17-4 Standard Enthalpies of Formation (kJ mol-1) H2(g) O2(g) C(s) Al(s) Fe(s) N2(g) Summary 0 +218 +249 +473 C (g) CO2 (g) H20 (l) H20 (g) +717 -394 -286 -242 CH3CH2OH (l) -278 -1274 -824 -1676 L17-5 H (g) O (g) N (g) C6H12O6 (s) Fe2O3 (s) Al2O3 (s) 2000 University of California How much is 100 W ? Chem 1A! Heat, Brain Ion Gradients 2000 University of California ~2 km/hr ~ 1m2 x ~ 10% L17-6 A.Pines,M.Kubinec,UCB L27-1 ChemQuiz 25.4 Compare the heat released in the following reactions (per mole). I C6H12O6 (s) + O2 (g) II Fe2O3 (s) + Al (s) 1) I > II A.Pines,M.Kubinec,UCB CO2 (g) + H2O (l) Fe (s) + Al2O3 (s) 3) I < II L27-2 2) I ~ II Bond Dissociation Energies X Summary Ex-y Ex- Y X + Y X + Y X Y Bond Energies and Reaction Enthalpies Atoms Ex-y(R) E -Ex-y(P) E -Ex-y Ex- Reactants H H= Ex-y(R) -Ex-y(P) Products L21-6 A.Pines,M.Kubinec,UCB L21-4 A.Pines,M.Kubinec,UCB A.Pines,M.Kubinec,UCB 1 Chem1A, L26: "Bond Energies" Bond Dissociation Energies X Y X + Y X + Y X Y E Ex-y Ex- -Ex-y Ex- A.Pines,M.Kubinec,UCB L27-5 ChemQuiz 26.1 When one mole of C (s) is atomized, how atomized, many moles of C-C bonds are broken ? 1) 1 A.Pines,M.Kubinec,UCB 2) 2 3) 4 L27-6 Bond Energies and Reaction Enthalpies Atoms Ex-y(R) (R) E -Ex-y(P) (P) (P) (R) Hf = Ex-y(R) -Ex-y(P) Reactants Elements Hf A.Pines,M.Kubinec,UCB Products Compounds L27-8 A.Pines,M.Kubinec,UCB 2 Chem1A, L26: "Bond Energies" Standard Enthalpies of Formation (kJ mol-1) H2(g) O2(g) C(s) Al(s) Fe(s) N2(g) (g) 0 +218 +249 +473 C (g) CO2 (g) H20 (l) H20 (g) +717 -394 -286 -242 CH3CH2OH (l) -278 -1274 -124 -136 L27-9 H (g) O (g) N (g) C6H12O6 (s) C4H10 (g) C4H10 (g) iso A.Pines,M.Kubinec,UCB Average Bond Enthalpies (kJmol-1) (kJ C (g) H- H CO-Cl Cl-(g) Cl2 H20 O O- (l) HO=(g) 20 O 436 +717 -394 242 146 -286 497 -242 C (g) -C-C- CO2 (g) C = C H2 (l) - C 0 C- +717 348 -394 612 -286 838 413 -242 C -O -C(g) CO O 2 H H20(g) ) H-Cl +717 360 -394 463 -286 431 946 -242 L27-10 - C (g) H20 -H N N H20 (g) A.Pines,M.Kubinec,UCB The polymerization of ethylene to polyethylene is: H2C CH2 H2C CH2 H2C CH2 ChemQuiz 26.2 CH2 CH2 CH2 CH2 CH2 CH2 ... 1) Endothermic 2) Isothermic 3) Exothermic L27-11 A.Pines,M.Kubinec,UCB A.Pines,M.Kubinec,UCB 3 Chem1A, L26: "Bond Energies" ChemQuiz 26.3 The decomposition: decomposition: H2O2 H2O + 1/2 O2 is exothermic. What is the exothermic. molecular structure of H2O2? 1) H H 2) H-O=O-H 3) H O=O =O- O-O H L27-13 A.Pines,M.Kubinec,UCB ChemQuiz 26.4 Which butane combustion reaction will release the most heat? 0.1 mole C4H10 0.1 mole 1) 0.1 mole C4H10 2) 0.2 mole C4H10 3) O2 A.Pines,M.Kubinec,UCB L27-15 Lecture Complete A.Pines,M.Kubinec,UCB L27-17 A.Pines,M.Kubinec,UCB 4 ...
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