8.2H 2 O 2H 2 + O 2 H-O-H + H-O-H H-H + H-H + O=O O=O H-H H-O released#required#kJ/molBond H 2 O kJ 2H 2 + O 2

2.Forming a bond releases energy 3.Breaking a bond requires energy 4.The energy required to break a chemical bond: the energy released when a bond is formed 5.Endothermic 6.Exothermic 7.a) H-F (568 kJ/mol) b) O-O (145 kJ/mol) 9. H-Cl Cl-Cl H-H released#required#kJ/molBond H 2 + Cl 2 2HCl kJ

d) theoretical: kJ, lab: 7500 kJ The lab value is about 50% of what it should have been because the calorimeter was very inefficient – lots of heat energy was lost. 10.a) O=O, H-O-H, O=C=O b) C 25 H O 2 25CO H 2 O c) C=O H-O O=O C-H C-C released#required#kJ/molBond

C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O kJ Thus,molar heat of combustion, Hc=1224 kJ/mol h = 1224 kJ/mol x 1 mol/46.08 g = 26.6 kJ/g 11.C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O O=O H-O C-O C=O C-H C-C released#required#kJ/molBond For more lessons, visit