CHEM 2E03 Chapter Notes - Chapter 6: Hyperconjugation, Unpaired Electron, Methyl Group
Document Summary
H is the amount of energy necessary to break the bond homolytically. Hemolytic bond cleavage: generates two uncharged species called radicals, each of which bairs an unpaired electron. Heterolytic bond cleavage: generates charged species called ions, one of the products carries the electron pair from the bond and is negatively charged while the other is left positive. Every bond has an associated h = bond dissociation energy, generally representing the energy associated with hemolytic cleavage. H = bond dissociation energy under standard conditions ( pressure = 1 atm) Heat of reaction: the total change in enthalpy ( h ) for a reaction: sign (+/-) indicates the direction in which the energy is exchanged. Exothermic: h is negative; system gives energy to its surroundings ( increase in temp) Endothermic: h is positive, receives energy from its surroundings (decrease in temp) Enthalpy and entropy must both be considered when predicting whether a reaction will occur.
