Ch9(8)-CH10(1-3)Nov21FA08a

Ch9(8)-CH10(1-3)Nov21FA08a - CHEM 109 General Chemistry...

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CHEM 109 General Chemistry University of Nebraska FALL 2008 21 November 2008 ANNOUNCEMENTS:
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Bond Energy Exothermic reactions : the total energy of product bonds formed is more than that of reactant bonds broken – ΔH 0 rxn = ΣBE (reactant bonds broken) – ΣBE (product bonds formed) ____________ reactions : the total energy of product bonds formed is less than that of reactant bonds broken ΔH is negative ΔH is ________ A reaction is exothermic when weak bonds break and strong bonds form. A reaction is endothermic when _____ bonds break and _______ bonds form.
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Bond Energy Using the STP sheet , calculate ΔH 0 rxn for the following reaction: CH 4 (g) + 2O 2 CO 2 (g) + 2H 2 O(g) Is the reaction endothermic or exothermic? On your STP sheet notice that C=O bonds in CO 2 have a different bond energy than C=O bonds in other compounds
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Bond Energy Using the STP sheet , calculate ΔH 0 rxn for the following reaction: CO 2 (g) + 2NH 3 (g) (NH 2 ) 2 CO(l) + H 2 O(l) Is the reaction endothermic or exothermic?
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Bond Lengths and Energies Two important properties of bonds Bond _______ – the nuclear separation distance where the molecule is most stable. (we usually speak of average bond length ) Bond _______ – the stability of a chemical bond (the lower the energy, the _____ the stability)
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1. Bond strength ________ as more electrons are shared between the atoms 1. Bond strength ________ as the electronegativity difference (∆χ) between bonded atoms increases. 1. Bond strength _______ as bonds become
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Ch9(8)-CH10(1-3)Nov21FA08a - CHEM 109 General Chemistry...

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