Kinetic Theory of Matter
Describes matter from both external (shape, volume, mass, temperature, pressure) and internal perspectives (molecular behavior). Explanations often require descriptions in terms of molecules or particles.
States of Matter
Solids: Fixed shape and volume. Molecules have very small spaces, regular arrangement, vibrate in fixed positions, and strong bonds.
Liquids: Fixed volume, shape adapts to the container. Molecules have small spaces, random arrangement, slide over each other, and strong bonds.
Gases: No fixed shape or volume. Molecules are far apart, no arrangement, move freely and fast, and have weak bonds.
Temperature
Defined as the average kinetic energy of molecules in a substance.
Temperature Scales
Celsius (°C): Has negative values.
Kelvin (K): Absolute temperature scale, no negative values. 0 K is absolute zero.
Absolute Zero
Lowest possible temperature where particles have minimal kinetic energy ($-273°Cor0 K).</p><h4id="0de4d414−3c26−4585−b71b−126650118ae8"data−toc−id="0de4d414−3c26−4585−b71b−126650118ae8"collapsed="false"seolevelmigrated="true">CelsiustoKelvinConversion</h4><ul><li><p>CelsiustoKelvin:K = °C + 273</p></li><li><p>KelvintoCelsius:°C = K - 273</p></li></ul><h3id="4d655a4a−dfbf−4fda−a9dd−2a611127c589"data−toc−id="4d655a4a−dfbf−4fda−a9dd−2a611127c589"collapsed="false"seolevelmigrated="true">ChangesofState</h3><ul><li><p>Melting:Solidtoliquid.</p></li><li><p>Boiling:Liquidtogas.</p></li><li><p>Condensation:Gastoliquid.</p></li><li><p>Freezing/Solidification:Liquidtosolid.</p></li></ul><p>Meltingandfreezingoccuratthemeltingpoint;boilingandcondensationoccurattheboilingpoint.</p><h4id="5fd1744f−cc81−4f30−ab1a−55c5bf4e8ac5"data−toc−id="5fd1744f−cc81−4f30−ab1a−55c5bf4e8ac5"collapsed="false"seolevelmigrated="true">HeatingCurve</h4><p>Temperatureremainsconstantduringmeltingandboilingasenergyisusedtobreakbondsbetweenmolecules,nottoincreasekineticenergy.</p><h3id="4b097cfc−9115−4c13−8b0f−9a1a50afcfcf"data−toc−id="4b097cfc−9115−4c13−8b0f−9a1a50afcfcf"collapsed="false"seolevelmigrated="true">Evaporationvs.Boiling</h3><ul><li><p><strong>Evaporation:</strong>Occursatanytemperature,involvesonlythemostenergeticmoleculesonthesurface,coolstheremainingliquid.</p></li><li><p><strong>Boiling:</strong>Occursattheboilingpoint,formsbubblesthroughouttheliquid,temperatureremainsconstant.</p></li></ul><h4id="29d1d2cb−048d−4513−a397−0551d361d7cb"data−toc−id="29d1d2cb−048d−4513−a397−0551d361d7cb"collapsed="false"seolevelmigrated="true">FactorsIncreasingEvaporationRate</h4><p>Increasingtemperature,increasingsurfacearea,aircurrents.</p><h3id="f660eb19−174e−4fad−afef−192e74061cfd"data−toc−id="f660eb19−174e−4fad−afef−192e74061cfd"collapsed="false"seolevelmigrated="true">AbsoluteZero</h3><p>Lowestpossibletemperaturewhereparticleshavetheleastkineticenergy.</p><h3id="faab6fef−d328−439c−8619−a3d1d4dbdd39"data−toc−id="faab6fef−d328−439c−8619−a3d1d4dbdd39"collapsed="false"seolevelmigrated="true">ThermalExpansion</h3><p>Increaseinvolumeofasubstanceduetoincreasedtemperature.</p><p>Moleculesmovefasterandfartherapart,butmoleculesthemselvesdonotexpand.</p><h4id="e0b5e10f−aac7−49a7−9b8d−2563e3e0697b"data−toc−id="e0b5e10f−aac7−49a7−9b8d−2563e3e0697b"collapsed="false"seolevelmigrated="true">FactorsAffectingExpansion:</h4><ul><li><p>Temperature.</p></li><li><p>Initialvolume.</p></li><li><p>State(gasesexpandmorethanliquids,liquidsmorethansolids).</p></li></ul><h4id="29dca6e4−98f1−4de1−8e98−232f603168e6"data−toc−id="29dca6e4−98f1−4de1−8e98−232f603168e6"collapsed="false"seolevelmigrated="true">UsesofThermalExpansion</h4><p>Thermometers,fittingringsonwheels(heatingexpandsthering),bimetallicstrips(usedinthermostatsandfirealarms).</p><h4id="74a7dfad−a696−4c21−8ae2−fd90984b3117"data−toc−id="74a7dfad−a696−4c21−8ae2−fd90984b3117"collapsed="false"seolevelmigrated="true">ProblemsCausedbyThermalExpansion</h4><p>Deformationofrailwaytracks(solvedbyleavinggaps),bridges/roads(expansionjoints),andelectriccables(sagginginsummer,contractioninwinter).</p><h3id="ffee6d8a−e3b1−4aca−bdfd−442fd77c9220"data−toc−id="ffee6d8a−e3b1−4aca−bdfd−442fd77c9220"collapsed="false"seolevelmigrated="true">Gases</h3><h4id="0775470d−e92a−463b−991f−c2d7c3093995"data−toc−id="0775470d−e92a−463b−991f−c2d7c3093995"collapsed="false"seolevelmigrated="true">BrownianMotion</h4><p>Randomandjerkymovementofsmokeparticles(orpollengrainsinwater)duetocollisionswithairmolecules.</p><h4id="57a55a08−70db−4d2f−ab7f−cec2f659283d"data−toc−id="57a55a08−70db−4d2f−ab7f−cec2f659283d"collapsed="false"seolevelmigrated="true">GasPressure</h4><p>Gasparticlescollidewithcontainerwalls,experiencingachangeinmomentum.Thischangeinmomentumovertimeappliesforce,andforceoverareaequalspressure.</p><h5id="e568d0d3−d751−4f7f−a157−b5313697318d"data−toc−id="e568d0d3−d751−4f7f−a157−b5313697318d"collapsed="false"seolevelmigrated="true">FactorsAffectingGasPressure</h5><ul><li><p><strong>Temperature:</strong>(atconstantvolume)Increasedtemperatureleadstofaster,morefrequentcollisions,increasingpressure(directlyproportional).</p></li><li><p><strong>Volume:</strong>(atconstanttemperature)Decreasedvolumeleadstomorefrequentcollisions,increasingpressure(inverselyproportional).</p></li></ul><h5id="51f08c1d−4e6a−46bb−9166−3606c866f4a2"data−toc−id="51f08c1d−4e6a−46bb−9166−3606c866f4a2"collapsed="false"seolevelmigrated="true">Boyle′sLaw</h5><p>PV = constantorP1V1 = P2V2</p><h3id="6c2b7169−73a9−4067−99ba−b4ea790b16e0"data−toc−id="6c2b7169−73a9−4067−99ba−b4ea790b16e0"collapsed="false"seolevelmigrated="true">SpecificHeatCapacity</h3><p>Energyneededtoraisethetemperatureof1kgofasubstanceby1°Cor1 K.</p><h4id="c0dcef13−5fb2−4f23−bb8a−842782b5bc56"data−toc−id="c0dcef13−5fb2−4f23−bb8a−842782b5bc56"collapsed="false"seolevelmigrated="true">Formula</h4><p>E = mcΔTwhereEisenergy,mismass,cisspecificheatcapacity,andΔT$$ is the change in temperature.
Experiment
Measure mass, initial and final temperatures, power, and time to determine specific heat capacity.
Sources of Error
Heat loss to surroundings; insulate to minimize.
Heat Transfer
Conduction
Nonmetals: Atoms vibrate and transfer heat to nearby atoms.
Metals: Also involve free-moving electrons that transfer heat to distant atoms. Metals are good conductors; insulators (plastic, wood) are bad conductors.
Convection
Hot liquids/gases expand, become less dense, and rise; cold liquids/gases are more dense and sink, creating convection currents.
Radiation
Heat transfer via electromagnetic waves (infrared). Everything emits infrared waves. Dull black surfaces are best at absorbing and emitting; shiny white surfaces are worst.
Constant Temperature
Indicates a balance between absorption and emission of radiation.
Vacuum Flask
Minimizes heat transfer: vacuum stops conduction and convection, silvered surfaces reduce radiation, lid prevents evaporation and convection.