CHEM 1310 Lecture Notes - Bond-Dissociation Energy, State Function, Chocolate Chip Cookie

• School: University of Manitoba
• Department: Chemistry
• Course: CHEM 1310
• Professor: Sarrah Vakili

Document Summary

Internal energy - based on work and q. State function - constant, only changes in terms of size. Energy required to break 1 mol of chemical bonds into the gaseous phase. Also known as bond enthalpy and bond dissociation energy. Will always be positive in value for the breaking of bonds: break bonds - positive, create bonds - negative. For reactions it may be: exothermic - stronger bonds in products then reactants - more stable products, endothermic - stronger bonds in reactants then products. Estimate e for the reaction: ethane + air carbon dioxide + water. 2c2h6 + 7o2 4co2 + 6h2o. Note: co2 energy for c-o is different then other c=o bonds. Bonds to break: 6 c-h bonds, 1 c-c bonds, 7/2 o=o bonds. 2 x 2 c=o bonds: 4 bonds total. Ereacttants = [6 e (c-h) + 1 e(c-o) + 7/2 e(o=o) - [4 e(c=o) + 6 e(h-o)]