1 Chapter 9 Energy , Enthalpy, & Thermochemistry oEnergy Facts oInternal Energy oEnthalpy oHess’s LawoHeating Curve oCalorimetry oH2Fuel 1 Big Idea:Heat and work are equivalent ways of changing the energy of a system. The total energy of an isolated system is constant. The change in enthalpy of a reaction indicates whether a reaction is endothermic or exothermic. Chapter 9: Energy, Enthalpy, and Thermochemistry Energy Facts Source of Energy Percent Petroleum 35.3% Coal 27.0% Natural Gas 20.3% Renewable 12.3% Nuclear 5.0% Global Sources of Energy 2006 http://news.cnet.com/8301-11128_3-9928068-54.html 2 Chapter 9: Energy, Enthalpy, and Thermochemistry Energy Facts Country Energy Consumption (Quadrillion Btu) United States 99.530 China 85.059 Russia 30.425 Japan 22.297 India 19.954 Germany 14.356 Canada 14.029 France 11.290 Brazil 10.629 Korea, South 9.886 Iran 8.120 Italy 7.896 Mexico 7.308 Saudi Arabia 6.727 Spain 6.504 Country Energy Consumption/person (MBtu) Canada 421.298 United States 326.864 Saudi Arabia 239.414 Russia 214.418 Korea, South 203.422 France 182.102 Germany 174.658 Japan 174.607 Spain 139.885 Italy 131.836 Iran 112.474 Mexico 67.864 China 54.483 Brazil 42.735 India 17.362 2008 http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=44&pid=44&aid=2 http://www.prb.org/Publications/Datasheets/2008/2008wpds.aspx 3 Chapter 9: Energy, Enthalpy, and Thermochemistry Energy Facts Source of Energy Percent World Percent US Petroleum 35.82% 37.4% Natural Gas 22.08% 24.8% Coal 28.68% 20.9% Renewable 7.38% 8.2% Nuclear 5.03% 8.8% US Sources of Energy 2009 (Quadrillion Btu) http://www.eia.doe.gov/aer/pecss_diagram.html http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm 4 Interesting energy facts about UCSB http://energy.ucsb.edu/ Chapter 9: Energy, Enthalpy, and Thermochemistry Internal Energy System: The object of study. Surrounding: The region outside the system. Internal Energy (E): The capacity to do work or to produce heat. Temperature (T): How hot or cold an object is. Heat (q): The energy that is transferred as a result of a temperature difference between a system and its surroundings. Work (w): The energy expended during the act of moving an object against an opposing force. 5 Note: If heat enters the system qis positive (endothermic reaction). If heat leaves the system qis negative (exothermic reaction). Note: If the system expands, wis negative. If the system contracts, wis positive. Chapter 9: Energy, Enthalpy, and Thermochemistry Student Question Internal Energy Which of these changes results in an increase in the internal energy of the system? a)The system absorbsheat and doeswork on the surroundings. b)The system releasesheat and doeswork on the surroundings. c)The system absorbsheat and haswork done on it by the surroundings. d)The system releasesheat and haswork done on it by the surroundings. 6
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