H-H Bond energy: 436 kJ/mol Bond Energy Name Chem Worksheet 16-2 Bond energy is defined as the amount of energy required

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H H Bond Energy 436 Kj Mol Bond Energy Name Chem Worksheet 16 2 Bond Energy Is Defined As The Amount Of Energy Required 1 (156.54 KiB) Viewed 6 times

H-H Bond energy: 436 kJ/mol Bond Energy Name Chem Worksheet 16-2 Bond energy is defined as the amount of energy required to break a bond. These values are positive, indicating that bond breaking is endothermic. Bond energies are reported in kilojoules per mole (kJ/mol). The energy for breaking a hydrogen-hydrogen bond is 436 kJ/mol so when a hydrogen-hydrogen bond is formed the process releases 436 kJ/mol. In a chemical reaction several bonds are broken and formed. For example in the reaction below a hydrogen-hydrogen bond is broken and a fluorine-fluorine bond is broken. Two hydrogen-fluorine bonds are formed. The overall energy change for this process is calculated below. example H2(g) + F2 (g) → 2HF AH n = [energy used for breaking bonds] - [energy formed in making bonds] [436 kJ/mol + 155 kJ/mol] – [2(567 kJ/mol)] = -543 kJ/mol F-F Bond Energy: 155 kJ/mol H-F Bond Energy: 567 kJ/mol 20 E = HH H-CI H-F N-H N-O O-H 0-0 F-F 436 kJ/mol 431 kJ/mol 567 kJ/mol 391 kJ/mol 201 kJ/mol 463 kJ/mol 146 kJ/mol 155 kJ/mol Average Bond Energies (kJ/mol) C-H 413 kJ/mol C-C 348 kJ/mol C-N 293 kJ/mol C-0 358 kJ/mol 485 kJ/mol 328 kJ/mol 259 kJ/mol CI-CI 242 kJ/mol CEC С=С C=0 O=0 CEO CEN NEN NEN CEN 614 kJ/mol 839 kJ/mol 799 kJ/mol 495 kJ/mol 1072 kJ/mol 615 kJ/mol 418 kJ/mol 941 kJ/mol 891 kJ/mol Estimate the enthalpy change (AH,xn) of the following reactions using the bond energies above. 1. H-H + CI- CH-CI + H-CI 4. CI H-C-Cl + O CI O=O- H-CI C-CI + CI HH 2. HH HC=CH + F-F 5. H ! O=0 H-C-H + O=0 H H-C-Ç-H F F O=C=O + H-O-H H-O-H H H H H 3. H-9-0-H + H-C-O-H → H-C-0-C-H 160# - #6-04 + H-O-H H H H H + Draw Lewis structures for reactants and products. Estimate the enthalpy change (AH,xn) for the reactions using bond energies. 6. H. (8) + CO2(g) → H20 (8) + CO (g) 10. H, (g) + CH (8) CH. (8) 7. 2H-0, (8) + 2H-0 (g) + O2 (8) 11. 2CH (8) + 70, (8) 4CO2 () + 6H20 (8) 8. CO (8) + 2H2 (8) CH,OH (8) 12. CH4 (8) + 3Cl2 (8) - CHCI; (g) + 3HCI (8) 9. N(g) + 3H2 (8) + 2NH3 (8) 13. HCN (g) + 2H, () CH_NH (8) John Erickson, 2005 WS16-2BondEnergy