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Unformatted text preview: Chapter 9 Reading Notes 9.1 The Nature of Energy Energy the capacity to do work or to produce heat Law of conservation of energy energy can be converted from one form to another but can neither be created nor destroyed Potential Energy energy due to position or composition. Ex: Water behind a dam. Attractive and repulsive forces. Kinetic Energy due to the motion of the object. Heat involves the transfer of energy due to temperature difference Work force acting over a distance. Energy change is independent of the pathway, but work and heat are both dependent on the pathway. State function refers to a property of the system that depends only on its present state. A state function does not depend in any way on the system's past or future. The value of a state function does not depend on how the system arrived at the present state, it depends only on the characteristics of the present state. One very important characteristic of a state function is that a change in this function in going from one state to another state is independent f the particular pathway taken between the two states. Energy is a state function, but work and heat are not state functions System part of the universe on which we wish to focus attention. The reactants and the products of the reaction Surroundings include everything else in the universe. Container, room and everything else other than the reactants and the products. Exothermic reaction that results in the evolution of heat, energy flows OUT of the system via heat. EX: Combustion of methane, energy flows out of the system as heat. Where does the energy released as heat come from in an exothermic reaction? The answer lies in the difference in potential energy between the products and the reactants....
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- Spring '08