ENERGY Reading Supplemental Text Materials Chapter 11 pages 225 238 Energy Ability to do work Unit Joule J J kg x m2 s2 Power Energy over time Watts W 1 W 1J s Power is energy over time http www dodgeglobe com images 102901 hiker jpg Types of Energy Mechanical Electrical Chemical Radiant Light Heat Nuclear Mechanical Energy Potential Energy Kinetic Energy Potential Energy Stored energy Kinetic Energy Energy of motion Energy Conversion From high grade to lower grade forms Energy conversion Mechanical to Electrical Energy conversion Chemical to mechanical Energy conversion Radiant to heat Radiant to electrical Steam Turbine http www uaf edu energyin webpage pages heat engines steam and gas turbines htm Earth s Energy Sun 99 of Earth s energy Internal heat radioactive decay gravitational pressure Sun s Energy Radiant energy Released by fusion Hydrogen fused into Helium 1 73 x 1017 watts received by Earth from Sun Converted by plants into chemical energy Photosynthesis 6 CO2 6 H2O sun energy C6H12O6 O2 Converts CO2 and H2O to sugar and O2 Created the level of oxygen present in today s atmosphere Ancient algae in Archean and Proterozoic oceans released O2 by photosynthesis Source of energy not from Sun Rare deep sea vent communities Sulfurous hotsprings supports bacteria Other organisms subsist on bacteria Larger creatures can survive on the bacteria eating organisms Black Smoker http www punaridge org doc factoids Biology Vent community http www punaridge org doc factoids Biology Tube worm and crab http www punaridge org doc factoids Biology Energy and Chemical Reactions Temperature affects rate of reactions More molecule collisions More energy to break chemical bonds Concentration of reactants Presence of catalyst Peroxide 2 H2O2 2 H2O O2 proceeds slowly Add platinum takes seconds not years Energy and Chemical Reactions Heat released or consumed in chemical reactions Measured in calories Food calorie is a kilocalorie kcal 1 Joule 0 24 calories Energy shown in equation C3H8 5 O2 3 CO2 4 H2O 526 kcal Reaction energy EXOTHERMIC heats up environment ENDOTHERMIC absorbs heat from environment Exothermic Reaction C3H8 5 O2 3 CO2 4 H2O 526 kcal Burn 2 moles of propane 2 x 526 kcal 1052 kcal Burn 308 g of propane 308 g 1 mole 44g 7 moles 7 moles x 526 kcal 3682 kcal Endothermic reaction N2 O2 4 32 kcal 2 NO 5 moles of nitrogen reacting with 5 moles of oxygen Consumes 5 x 4 32 kcal 21 6 kcal Conservation of Energy Energy is not created or destroyed First Law of Thermodynamics Heat Flow From objects with heat to those with less Change form from high quality to lower quality Chemical to heat friction Entropy Lack of order of systems Nature tends toward disorder greater entropy Takes energy to overcome entropy Oil spill on Columbia River CFC released into atmosphere Energy sources Wood chemical energy stored by plants Kinetic energy Water power to grind grain Wind to pump water Fossil fuels Fossil fuels Burn readily Reaction is oxidation Release heat energy Fossil fuels Coal Petroleum Natural Gas First law of thermodynamics Conservation of energy Cannot create or destroy energy But we can convert to less useful form Fossil fuels Non renewable From ancient organisms Extracted from Earth Coal C O2 CO2 Anthracite Bitumen Lignite Coal Incompletely decayed plants Burial pressure releases O2 and H2 Carbon remains Paleozoic Pennsylvanian coal Carboniferous Era Carboniferous Period Forest http palaeos com Paleozoic Carboniferous Carboniferous htm Coal formation 1 Coal formation 2 Coal formation 3 Coal formation 4 Coal formation Summary Coal Must be mined Pollutants in coal Sulfur leads to acid rain Also contains mercury arsenic nitrates Coal Coke is made by heating coal Byproduct refined into organic chemicals Natural Gas Mostly methane CH4 2 O2 CO2 2 H2O heat Excellent clean burning fuel Raw material for plastics and other chemicals Petroleum Replaced coal by about 1950 Complex hydrocarbon molecules Derived from fats Combustion products are carbon dioxide and water Petroleum C8H18 18 O2 16 CO2 18 H2O Also contains some sulfur compounds Fuel oil is fairly clean Burning gasoline results in smog Internal combustion engines inefficient
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