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What is energy?The ability to do workThe ability to transfer heat

Two types: Potential and KineticPage 2Potential EnergyStored EnergyEnergy due toPositionChemical BondsNuclearPosition: boulder at the top of the hillChemical: tank of gas, hamburgerNuclear: atomic bomb, nuclear reactor

Kinetic EnergyActive EnergyEnergy of MotionElectromagnetic waves, (ex. Light, Xrays)HeatMotionElectrical current, A moving truck has the ability to flatten you - do work on you!Kinetic and Potential Energy

Electromagnetic SpectrumFirst Law of ThermodynamicsEnergy can neither be created nor destroyed, but may change from one form to another.

Page 2 bottomEntropy 2nd LawEntropy is the amount of disorder in a systemEntropy always increases over time (in the absence of an input of outside energy)Example: cleaning up your room

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Page 4Exothermic vs Endothermic

Chemical OR Physical changes can be exothermic or endothermic.12EndothermicExothermicDefinitionStored energyEnergy of motionEnergy isAbsorbedReleasedTemperature+HChemical -TPhysical +T-HChemical +TPhysical -TType of Energy ConversionExample2H2O + energy 2H2 + O2Energy is on the left2H2 + O2 2H2O + energyEnergy is on the right

A hot pack contains chemicals that can be activated to produce heat. A cold pack contains chemicals that feel cold when activated.Based on energy flow, state the type of chemical change that occurs in a hot pack. ExothermicA cold pack is placed on an injured leg. Indicate the direction of the flow of energy between the leg and the cold pack. From the leg to the cold pack (Hot to Cold)What is the Law of Conservation of Energy? Describe how the Law of Conservation of Energy applies to the chemical reaction that occurs in the hot pack. Energy cannot be created nor destroyed. It can only be changed from one form to another. The heat produced in the hot pack was stored in the chemical bonds.

Regents Question: 06/02 #64-6614Page 5Measuring EnergyEnergyThere are two units which are commonly used:Calories (c): amount of energy it takes to raise one gram of water one degree CelsiusJoules (J): 4.18 Joules = 1 calorieMetric system is most commonly used in chemistryCriteriaHeatTemperatureSimilar/DifferentEnergyKineticMotion of MoleculesBoth are about MotionQuantitative AspectHow fast molecules are moving. Measured by temperatureKelvin and CelsiusCelsius based on properties of water

Kelvin based on CelsiusDefinitionA form of Kinetic Energy that involves movement of moleculesThe measurement of how fast a molecule is movingTemperature is a measurement of Kinetic EnergyExamples

Page 6 Converting between Celsius and KelvinReference TableWhy is it not out already?Temperature Towards bottom K = C + 273Heat and TemperatureTemperature measures the average speed of the atoms

Heat is the amount of kinetic energy of the atoms

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To convert between Kelvin and Celsius use K=C+273J Deutsch 200321

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Phases of Matter- Page 9

IceRegularIrregularIrregularRegularRegularIrregularFastModerateMinimalIceIcePage 10Graph page 11 onto page 13. Be sure to have an appropriate scale. Circle the points and connect them.ABCDEFA change in phase is a change in Potential Energy, not Kinetic Energy28

Potential energy changes, so temperature doesntBoiling PointMelting Point

Energy and phase changesABsolid warms up (KE/PE constant) 30

Energy and phase changesABsolid warms up (KE/PE constant) BCsolid melts (KE constant/PE)32

Energy and phase changesABsolid warms up (KE/PE constant) BCsolid melts (KE constant/PE)CDliquid warms up (KE/PE constant) 34

Energy and phase changesABsolid warms up (KE/PE constant) BCsolid melts (KE constant/PE)CDliquid warms up (KE/PE constant) DEliquid boils (KE constant/PE)36

Energy and phase changesABsolid warms up (KE/PE constant) BCsolid melts (KE constant/PE)CDliquid warms up (KE/PE constant) DEliquid boils (KE constant/PE)EFgas warms (KE/PE constant) 38

Regents Question: 06/02 #28J Deutsch 200340As ice melts at standard pressure, its temperature remains at 0C until it has completely melted. Its potential energy(1) decreases(2) increases(3) remains the same

Regents Question: 08/02 #54J Deutsch 200341

A sample of water is heated from a liquid at 40C to a gas at 110C. The graph of the heating curve is shown in your answer booklet. a On the heating curve diagram provided in your answer booklet, label each of the following regions:Liquid, onlyGas, onlyPhase change

Liquid OnlyGas OnlyPhase changeRegents Question: contdJ Deutsch 200342

b For section QR of the graph, state what is happening to the water molecules as heat is added.

c For section RS of the graph, state what is happening to the water molecules as heat is added.

They move faster, their temperature increases.Their intermolecular bonds are breaking, their potential energy is increasing. Regents Question: 01/02 #47J Deutsch 200343

What is the melting point of this substance?(1) 30C(3) 90C(2) 55C (4) 120C

Graph page 14 onto page 16. Be sure to have an appropriate scale. Circle the points and connect them.

FEDCBAEnergy and phase changesABGas cools down (KE/PE constant) BCGas condenses (KE constant/PE )CDliquid cools down (KE /PE constant) DEliquid freezes (KE constant/PE )EFSolid cools down (KE /PE constant) 46Pages 17-18

Page 19How do we calculate amount of heat,(Q), if we are not given a graphic?3 equations for QQ = mCTQ = mHfQ = mHvHave to figure out which one to use for a given problem.Depends which section of heating curve.Look for hints in the problem.

Calculating Heat TransferredQ = mCT Simple system: Pure substance in a single phase. To calculate heat gained or lost, use:Q = amount of heat transferredm = mass of substanceC = specific heat capacity of the substance (Table B).T = temperature change = Tfinal Tinitial

Q = mCTTemperature changedTemperature increasedTemperature decreasedInitial / Start temperatureFinal temperatureEnding temperatureFrom ____ to ____WaterHfAmount of energy required to convert 1 gram of a pure substance from the solid to the liquid phase at the melting point.

Heat of FusionCalculating Energy Change at Phase ChangeQ = mHfUse this equation to calculate energy changes for phase changes between ice & liquid water at 0C.Q = mHfIceFreezingMeltingAt 0C (for H2O)At constant temperatureHvAmount of energy required to convert 1 gram of a pure substance from the liquid to the gas phase at the boiling point.

Heat of VaporizationCalculating Energy Change at Phase ChangeQ = mHvUse this equation to calculate energy changes for phase changes between steam & liquid water at 100C.Q = mHvSteamBoilingCondensationAt 100C (for H2O)At constant temperature