23 chem notes - Thermochemistry-Chemistry of Heat Chapter 5 Energy the ability to do work or transfer heat o Work energy used to cause an object

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9/23/08 Thermochemistry-Chemistry of Heat -- Chapter 5 Energy: the ability to do work or transfer heat o Work: energy used to cause an object that has mass to move o Energy used to cause the temperature of an object to rise Potential energy: energy an object possesses by virtue of its position or chemical composition Kinetic energy: energy an object possesses by virtue of its motion. KE=1/2 mv^2 Units of Energy The SI unit of energy is the joule (J)---- 1 J=1 kgm^2/s^2 An older, non-si unit is still in widespread use: the calorie (cal)---- 1 cal= 4.184 J System and Surroundings The system includes the molecules we want to study The surroundings include everything else Work Energy used to move an object over some distance. w= Fxd, where w is work, F is the force, and d is the distance over which the force is exerted Heat Energy can also be transferred as heat. Heat flows from warmer objects to cooler objects. Transferal of Energy a.) The potential energy of this ball of clay is increased when it is moved from the ground to the top of the wall b.) As the ball falls, its potential energy is converted to kinetic energy c.) When it hits the ground, its kinetic energy falls to zero (since it is no longer moving); some of the energy does work on the ball, the rest is dissipated as heat First Law of Thermodynamics Energy is neither created nor destroyed. In other words, the total energy of the universe is a constant; if the system loses energy, it must be
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This note was uploaded on 09/28/2008 for the course BIO 1020 taught by Professor Parish during the Spring '08 term at Auburn University.

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23 chem notes - Thermochemistry-Chemistry of Heat Chapter 5 Energy the ability to do work or transfer heat o Work energy used to cause an object

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