Chap06notes - AP Chemistry A Allan Chapter Six Notes Thermochemistry 6.1 The Nature of Energy A Definition 1 Energy is the capacity to do work(or

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AP Chemistry A. Allan Chapter Six Notes - Thermochemistry 6.1 The Nature of Energy A. Definition 1. Energy is the capacity to do work (or to produce heat*) a. Work is a force acting over a distance (moving an object) b. *Heat is actually a form of energy. (1) chemicals may store potential energy in their bonds that can be released as heat energy B. Law of Conservation of Energy 1. Energy can be converted from one form to another, but cannot be created or destroyed a. Potential energy (1) energy due to position or composition b. Kinetic energy (1) energy due to the motion of an object (2) v m KE 2 2 1 = C. Heat and Temperature 1. Temperature reflects random motion of particles in a substance 2. Temperature indicates the direction in which heat energy will flow 3. Heat is a measure of energy content 4. Heat is what is transferred during a temperature change D. State Functions 1. A property of a system that depends only on its present state. 2. State functions do not depend on what has happened in the system, or what might happen in the system in the future 3. State functions are independent of the pathway taken to get to that state. Example: a liter of water behind a dam has the same potential energy for work regardless of whether it flowed downhill to the dam, or was taken uphill to the dam in a bucket. The potential energy is a state function dependent only on the current position of the water, not on how the water got there. E. Chemical Energy 1. Exothermic reactions a. Reactions that give off energy as they progress b. Some of the potential energy stored in the chemical bonds is converted to thermal energy (random KE) through heat c. Products are generally more stable (stronger bonds) than reactants 2. Endothermic reactions a. Reactions in which energy is absorbed from the surroundings b. Energy flows into the system to increase the potential energy of the system
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c. Products are generally less stable (weaker bonds) than the reactants F. Thermodynamics 1. System Energy w q E + = a. q = heat (1) q is positive in endothermic reactions
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This note was uploaded on 09/28/2009 for the course CHEM 102 taught by Professor Freeman during the Spring '08 term at South Carolina.

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Chap06notes - AP Chemistry A Allan Chapter Six Notes Thermochemistry 6.1 The Nature of Energy A Definition 1 Energy is the capacity to do work(or

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