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Unformatted text preview: Chapter 5: Thermochemistry Chapter Summary Introduction and Section 5.1 Thermodynamics is the study of energy and its transformations. In this chapter we have focused on thermochemistry , the transformations of energy--especially heat--during chemical reactions. An object can possess energy in two forms: Kinetic energy is the energy due to motion of the object, and potential energy is the energy that an object possesses by virtue of its position relative to other objects. An electron in motion near a proton, for example, has kinetic energy because of its motion and potential energy because of its electrostatic attraction to the proton. The SI unit of energy is the joule (J): Another common energy unit is the calorie (cal), which was originally defined as the quantity of energy necessary to increase the temperature of 1 g of water by 1C: When we study thermodynamic properties, we define a specific amount of matter as the system . Everything outside the system is the surroundings . When we study a chemical reaction, the system is generally the reactants and products. A closed system can exchange energy, but not matter, with the surroundings. Energy can be transferred between the system and the surroundings as work or heat. Work is the energy expended to move an object against a force . Heat is the energy that is transferred from a hotter object to a colder one. Energy is the capacity to do work or to transfer heat. Section 5.2 The internal energy of a system is the sum of all the kinetic and potential energies of its component parts. The internal energy of a system can change because of energy transferred between the system and the parts....
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This note was uploaded on 04/17/2008 for the course ACHM 120 taught by Professor Shekhtman,alexander during the Spring '08 term at SUNY Albany.
- Spring '08