Chapter 5 Lecture

# Chapter 5 Lecture - 1 1...

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Unformatted text preview: 1 1 http://www.google.com/search?q=hydrogen+balloon+explosion&sourceid=navclient-ff&ie=UTF- 8&rlz=1B3GGGL_enUS233US234 2 Energy in Chemical Reactions Section 5.1 H H H H H H H H Candle H 2H 2(g) + O 2(g) 2 H 2 O (l) + ENERGY H H H H H H H H POW! Heat 3 Energy Relationships in Chemistry • Thermodynamics – study of energy and its transformations • First law of thermodynamics – energy can neither be created nor destroyed Section 5.1, 2 2 4 Energy capacity to do work or to transfer heat • kinetic energy – energy of motion; E k = 1/2 mv 2 • potential energy – stored energy Section 5.1 5 Nitrogen Triiodide Movie Section 5.1 6 Properties of Energy • Energy is an extensive property (depends on the amount of material). • Energy is a state function. – property of a system that is determined by specifying its condition or state (temperature, pressure, location, etc); the value of a state function does not depend on the particular history of the sample, only on its present condition Section 5.2 3 7 Units of Energy • The SI unit of energy is the joule (J). • A joule is not a large quantity of energy so we will frequently use kilojoules (kJ) in discussing chemical reactions. • An older, non-SI unit is still in widespread use: The calorie (cal). 1 cal = 4.184 J 1 J = 1 ⎯⎯ kg m 2 s 2 1 2 KE = ⎯ mv 2 = ½ (2kg)(1 m/s) 2 = 8 Basic Definitions • System – portion of the experiment singled out for study; usually the chemicals • Surroundings – everything else The system can not exchange matter with the surroundings, but the system can exchange energy with its surroundings. Section 5.1 9 System and Surroundings • The system includes the molecules we want to study (here, the hydrogen and oxygen molecules)....
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## This note was uploaded on 11/11/2009 for the course CHEM 1341 taught by Professor Compton during the Spring '08 term at Texas State.

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Chapter 5 Lecture - 1 1...

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