Heat and energy transfer Energy of phase change of water Water cycle y Groundwater Heat Calorie Amount of heat required to raise the temperature of 1 gram of pure water 1o C Food Calories Calories are kilocalories Joule of calorie 1 cal 4 184 J Laws of Thermodynamics 1 Conservation of energy and matter 2 Entropy is increased with conversion 3 No system can reach absolute zero C P Snow the British scientist and author has offered up an easy and funny way to remember the Three Laws He says they can be translated as 1 You cannot win you can t get something for nothing because matter and energy are conserved 2 You cannot break even you cannot return to the same energy state because entropy always increases 3 You cannot get out of the game because absolute zero is not attainable Heat Expansion Random motion causes substance to be bigger Liquids usually have greater heat expansion than solids Thermostats Th t t use different diff t expansion i off different type of metals Specific Heat Capacity Quantity of heat needed to change the temperature of given amount of a substance 1o C Water very Water very high specific heat capacity 1 calorie raises one gram of water 1 C 1 calorie raises one gram of rock 5o C Maritime areas more mild temperature than continental areas Water Expansion Unusual response to cooling Contracts until reaching 4o C Expands slightly upon further cooling to 0o C Expands 9 upon freezing http www alaskarails org terminology questions html http demo physics uiuc edu LectDemo scripts demo descript idc DemoID 40 Water Molecule Bent Polar P l Water Expansion Molecule shape fit together closer in liquid Open structured crystal due to hydrogen bonding of polar molecules upon freezing Heat Transfer conduction Tile is a better conductor of heat than the wood floor 1 Heat Transfer convection Currents from heater shown by shadows Heat Transfer radiation Does not need material to transfer radiant energy Dark bodies absorb it better than light colored light colored ones Radiant Energy All objects emit thermal energy Visible light above 500oC Re emit absorbed radiation at wavelength according to temperature Good absorbers are good emitters Poor absorbers are poor emitters Heat Transfer Conduction Direct molecule interaction Transferring energy to next molecule Convection C ti Movement of fluid liquid or gas Radiation Through open space Electromagnetic radiation Water Energy of Phase Change Energy of phase change for water Calorie energy to change 1 g water 1 K or 1 oC Also need energy to change to different state of matter Energy of vaporization condensation 540 calories per gram of water 2256 J g Energy of melting freezing 80 calories per gram 334 J g http hyperphysics phy astr gsu edu hbase thermo phase html Water Energy to melt ice Energy goes into breaking the bonds that are holding the molecules in fixed position with respect to one another 80 calories per gram of ice that melts Temperature remains constant during this Water Heat of Fusion Heat added to ice causes the phase change No change in temperature until all the ice is melted melted Heat taken up by water upon melting Heat released from water upon freezing 80 calories per gram of water that goes from frozen to liquid or liquid to frozen Water Heat of Vaporization Heat taken up by water upon vaporizing Heat added to water causes the phase change no change in temperature until all the water is vaporized vaporized Heat released from water upon condensing sometimes described as the heat of condensation 540 calories per gram of water that goes from vapor to liquid or liquid to vapor 2 In Class Activity In Class Activity In Class Activity How much energy is transferred to the environment when one gram of steam at 100o C condenses to water at 100o C How much energy is transferred to the environment when one gram of boiling water at 100o C cools to 0o C How much energy is transferred to the environment when one gram of water at 0o C freezes to ice at 0o C Energy of vaporization and condensation 540 calories gram of water Definition of calorie heat required to change the temperature of 1 gram of water 1o C Energy of melting and freezing of water 80 calories gram In Class Activity How much energy is transferred to the environment when one gram of steam at 100o C cools to 0o C and freezes to become ice Three phases of water Heat is released in this process Condense 1 g from steam to liquid 540 cal g x 1 g 540 cal released for condensation 100oC x 1 cal g x 1 g 100 cal released for cooling 80 cal g x 1 g 80 J to freeze Total these to get 720 calories are released Atmosphere Evaporation Energy goes into air Cools remaining water Condensation C d ti Energy goes from air to surface Warms local environment http www cdli ca CITE glaciers htm Water Cycle 86 of evaporation from sea surface 14 of atmospheric moisture from land as EVAPOTRANSPIRATION Water Cycle Water Cycle Less that 3 of Earth s water is on land Over of that is in glacial ice Most of the rest is stored as groundwater some groundwater is saline 78 of precipitation on sea surface 22 of water precipitated falls on land http meted com mesoprim mpradfog print htm 3 Groundwater Surface water Water Distribution Groundwater Water sources in Oregon Precipitation infiltrates Earth s surface Largest reservoir of liquid fresh water Drinking water source for half of U S http www deq state or us wq dwp dwp htm Groundwater Contributes to stream flow Universal solvent Dissolves some rock types Limestone CaCO3 Salts NaCl KCl Gypsum CaSO4 Groundwater terms diagram Groundwater Source First becomes soil moisture Plants use it Some evaporates directly Some sinks down Groundwater Terms Zone of saturation Water table Zone of aeration Infiltration Groundwater is stored Groundwater Storage Porosity of rock Spaces between sand grains Cracks in crystalline rock Dissolved cavities Permeability Groundwater Storage Stored in AQUIFER Porous and permeable rock Trapped by AQUITARD Impermeable I bl rock k Clay shale Allows water to move Interconnection of pore spaces 4 Groundwater Movement Groundwater movement diagram Spring Where water table intersects the ground su ace surface Very slowly Small openings High surface tension P Pressure forces f water t to t areas off lower l pressure Hydraulic gradient Hydraulic head Wells Ogallala supported agriculture Wells after drawdown Ogallala Aquifer Exploited in Great Plains agriculture Water table dropped Recharge rate low Artesian wells San Joaquin Valley
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