6.4 Bond Energy Bond breaking and bond forming Breaking bonds needs energy, energy is absorbed from the Therefore, bond breaking is an endothermic process. Forming bonds releases energy to the surroundings. Therefore, bond forming is an exothermic process. If the...
6.3 Hess' Law Hess' law and Hess' cycle Hess' law states that the total enthalpy change in a chemical reaction is independent of the route which the reaction takes place as long as the initial and final conditions are the same For example, the enthalpy change of...
6.1 Enthalpy Changes Exothermic and endothermic reactions Most chemical reactions are accompanied by energy changes. Some absorbs energy while some releases it An exothermic reaction is a reaction that releases energy to the surroundings. Therefore the product...
6.2 Standard Enthalpy Changes The standard condition To make comparison of enthalpy changes a fair comparison, same conditions must be used. These are called the standard conditions: A pressure of 100 kPa(approximately atmospheric pressure). A temperature of 298 K...
CHAPTER 6: Chemical Energetics Enthalpy Changes Standard Enthalpy Changes Hess' Law Bond Energy Learning outcomes: explain that some chemical reactions are accompanied by energy changes, principally in the form of heat energy; the energy changes can be...