1Heat and energy transferEnergy of phase change of waterWater cycleyGroundwaterHeat• Calorie– Amount of heat required to raise the temperature of 1 gram of pure water 1oC–Food‘Calories’are kilocaloriesFood Calories are kilocalories• Joule ~ ¼ of calorie– 1 cal. = 4.184 JSpecific Heat Capacity• Quantity of heat needed to change the temperature of given amount of a substance 1oC•Watervery high specific heat capacity•Water—very high specific heat capacity– 1 calorie raises one gram of water 1°C– 1 calorie raises one gram of rock ~5oC– Maritime areas more mild temperature than continental areasLaws of Thermodynamics1. Conservation of energy and matter2. Entropy is increased with conversion3. No system can reach absolute zeroC.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 solidsTh t t diff t i f•Thermostats use different expansion of different type of metalshttp://www.alaskarails.org/terminology/questions.html http://demo.physics.uiuc.edu/LectDemo/scripts/demo_descript.idc?DemoID=40Water Expansion• Unusual response to cooling• Contracts until reaching 4oCreaching 4oC • Expands slightly upon further cooling to 0oC• Expands 9% upon freezingWater Molecule• Bent Pl•PolarWater Expansion• Molecule shape fit together closer in liquid• Open structured crystal due to hydrogen bonding of polar molecules upon freezingHeat Transfer: conduction• Tile is a better conductor of heat than the wood floor2Heat Transfer: convection• Currents from heater shown by shadowsHeat Transfer: radiation• Does not need material to transfer radiant energy• Dark bodies absorb it better than lightcolored onesthan light-colored onesRadiant 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 emittersHeat Transfer• Conduction– Direct molecule interaction– Transferring energy to next moleculeCti•Convection– Movement of fluid: liquid or gas• Radiation– Through open space– Electromagnetic radiationWater: Energy of Phase Change• Calorie: energy to change 1 g water 1 K or 1 oC• Also need energy to change to different state of matterstate of matter• Energy of vaporization/condensation¾540 calories per gram of water = 2256 J/g• Energy of melting/freezing¾80 calories per gram= 334 J/g Energy of phase change for waterhttp://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.htmlWater: 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 meltedis 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 frozenWater 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 vaporizedthe water is 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 vapor3In-Class ActivityHow much energy is transferred to the environment when one gram of steam at 100oC condenses to water at 100oC?Energy of vaporization and condensation =540 calories/gram of waterIn-Class ActivityHow much energy is transferred to the environment when one gram of boiling water at 100oC cools to 0oC?Definition of calorie: heat required to change the temperature of 1 gram of water 1oCIn-Class ActivityHow much energy is transferred to the environment when one gram of water at 0oC freezes to ice at 0oC?Energy of melting and freezing of water80 calories/gramIn-Class ActivityHow much energy is transferred to the environment when one gram of steam at 100oC cools to 0oC and freezes to become ice?Heat is released in this processHeat is released in this process Condense 1 g from steam to liquid540 cal/g x 1 g = 540 cal released for condensation Δ100oC x 1 cal/g x 1 g = 100 cal released for cooling80 cal/g x 1 g = 80 J to freezeTotal these to get 720 calories are releasedThree phases of waterhttp://www.cdli.ca/CITE/glaciers.htmAtmosphere• Evaporation – Energy goes into air– Cools remaining waterCd ti•Condensation– Energy goes from air to surface– Warms local environmentWater Cycle• 86% of evaporation from sea surface• 14% of atmospheric moisture from land as EVAPOTRANSPIRATION• 78% of precipitation on sea surface• 22% of water precipitated falls on land http://meted.com/mesoprim/mpradfog/print.htmWater CycleWater Cycle• Less that 3% of Earth’s water is on land• Over ¾ of that is in glacial ice• Most of the rest is stored as groundwater–(some groundwater is saline)4Water DistributionGroundwater• Precipitation infiltrates Earth’s surface• Largest reservoir of liquid fresh water• Drinking water source for half of U.S.Water sources in OregonGroundwaterSurface waterhttp://www.deq.state.or.us/wq/dwp/dwp.htmGroundwater• Contributes to stream flow• ‘Universal solvent’• Dissolves some rock types–Limestone (CaCO3)– Salts (NaCl, KCl)– Gypsum (CaSO4)Groundwater Source• First becomes ‘soil moisture’– Plants use it– Some evaporates directlySome sinks down–Some sinks down• Infiltration• ‘Groundwater’ is storedGroundwater Terms• Zone of saturation• Water table• Zone of aerationGroundwater terms diagram Groundwater Storage • Porosity of rock– Spaces between sand grains– Cracks in crystalline rockDissolved cavities–Dissolved cavities• Permeability– Allows water to move– Interconnection of pore spaces• Stored in AQUIFER– Porous and permeable rock• Trapped by
View Full Document
Unlocking...