ENERGY. Energy. Power is energy over time. Power. Mechanical Energy. Types of Energy. Ability to do work Unit: Joule (J) J = (kg x m 2 )/s 2

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1 Energy ENERGY Ability to do work Unit: Joule (J) J = (kg x m 2 )/s 2 Reading: Supplemental Text Materials Chapter 11: pages Power Power is energy over time Energy over time Watts (W) 1 W = 1J/s Types of Energy Mechanical Electrical Chemical Radiant (Light) Heat Nuclear Mechanical Energy Potential Energy Kinetic Energy 1

2 Stored energy Potential 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 Radiant to heat Radiant to electrical Energy conversion 2

3 Steam Turbine 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 watts received by Earth from Sun Converted by plants into chemical energy Photosynthesis 6 CO H 2 O sun energy C 6 H 12 O 6 + O 2 Converts CO 2 and H 2 O to sugar and O 2 Created the level of oxygen present in today s atmosphere Ancient algae in Archean and Proterozoic oceans released O 2 by photosynthesis Source of energy not from Sun Black Smoker Rare deep sea vent communities Sulfurous hotsprings supports bacteria Other organisms subsist on bacteria Larger creatures can survive on the bacteria-eating organisms 3

4 Vent community Tube worm and crab 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 H 2 O 2 2 H 2 O + O 2 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 C 3 H O 2 3 CO H 2 O kcal Reaction energy EXOTHERMIC heats up environment ENDOTHERMIC absorbs heat from environment Exothermic Reaction C 3 H O 2 3 CO H 2 O 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 4

5 Endothermic reaction N 2 + O 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 5

6 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 + O 2 CO 2 Anthracite Bitumen Lignite Coal Carboniferous Period Forest Incompletely decayed plants Burial pressure releases O 2 and H 2 Carbon remains Paleozoic Pennsylvanian coal, Carboniferous Era 6

7 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 7

8 Coal Coke is made by heating coal Byproduct refined into organic chemicals Natural Gas Mostly methane CH O 2 CO H 2 O + 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 C 8 H O 2 16 CO H 2 O Also contains some sulfur compounds Fuel oil is fairly clean Burning gasoline results in smog Internal combustion engines inefficient 8