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Chapter 2Chapter 2

An Introduction ChemistryAn Introduction Chemistry

Lecture 5: Types of EnergyLecture 5: Types of Energy

•• Capacity to…Capacity to…•• Do workDo work

•• Transfer heatTransfer heat

•• Not matter!Not matter!•• Condition of the components of a systemCondition of the components of a system

EnergyEnergy

•• Many forms of energy, all either (pg 2Many forms of energy, all either (pg 2--16)…16)…•• KineticKinetic•• PotentialPotential

•• Energy is conservedEnergy is conserved•• Cannot be created or destroyedCannot be created or destroyed•• First Law of ThermodynamicsFirst Law of Thermodynamics

EnergyEnergy

•• Energy can change formsEnergy can change forms•• 4 types important in function of the body4 types important in function of the body

•• ThermalThermal•• ElectromagneticElectromagnetic

•• ElectricalElectrical•• ChemicalChemical

EnergyEnergy

•• Energy of random movement of particlesEnergy of random movement of particles

•• Measured by temperatureMeasured by temperature

Thermal EnergyThermal Energy

•• Measured in calories (or kilocalories or Calories)Measured in calories (or kilocalories or Calories)

•• Heat:Heat: Transfer of thermal energy between two Transfer of thermal energy between two objects at different temperaturesobjects at different temperatures

Thermal EnergyThermal Energy

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•• Consider two beakers…Consider two beakers…

Thermal EnergyThermal Energy

HOT!HOT!

WarmWarm

COLD!COLD!

WarmWarm•• Molecules Molecules move fastmove fast

•• More More collisionscollisions

•• More energyMore energytransfertransfer

•• Molecules Molecules move slowmove slow

•• FewerFewercollisionscollisions

•• Less energyLess energytransfertransfer

DirectionDirectionofof

heatheatflowflow

•• Energy associated with movement of photons Energy associated with movement of photons through spacethrough space

•• Energy content inversely proportional to Energy content inversely proportional to wavelengthwavelength

Electromagnetic EnergyElectromagnetic Energy

•• Energy associated with movement electrons or Energy associated with movement electrons or ions along a conductorions along a conductor

•• Important in sensory transduction, nerve Important in sensory transduction, nerve impulses, muscle contractionsimpulses, muscle contractions

Electrical EnergyElectrical Energy

•• What do all of these forms of energy have in What do all of these forms of energy have in common?common?

•• ThermalThermal

•• ElectromagneticElectromagnetic

•• ElectricalElectrical

QuestionQuestion

•• Something “moves”Something “moves”

•• Thermal = molecules, atoms, ionsThermal = molecules, atoms, ions

•• Electromagnetic = photonsElectromagnetic = photons

•• Electrical = charged particlesElectrical = charged particles

•• All three are forms of kinetic energy!All three are forms of kinetic energy!

AnswerAnswer

•• Energy stored in chemical bondsEnergy stored in chemical bonds

•• Potential energyPotential energy

•• Body’s primary energy source for metabolismBody’s primary energy source for metabolism

•• Many bonds = more energy storedMany bonds = more energy stored

Chemical EnergyChemical Energy

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•• Let’s consider a catabolic reactionLet’s consider a catabolic reaction

•• Reactants Reactants vsvs productsproducts

•• Which is moreWhich is more

complex?complex?

•• Which has more Which has more

potential energy?potential energy?

Chemical EnergyChemical Energy

•• Also called Also called exergonicexergonic reactionsreactions

•• Reactants are moreReactants are more

complexcomplex

•• Reactants have Reactants have

more potential energymore potential energy

Chemical EnergyChemical Energy

Potential energy

•• Let’s consider an anabolic reactionLet’s consider an anabolic reaction

•• Reactants Reactants vsvs productsproducts

•• Which is moreWhich is more

complex?complex?

•• Which has more Which has more

potential energy?potential energy?

Chemical EnergyChemical Energy

•• Also called Also called endergonicendergonic reactionsreactions

•• Products are moreProducts are more

complexcomplex

•• Products have more Products have more

potential energypotential energy

Chemical EnergyChemical Energy

Potential energy

•• EndergonicEndergonic reactions are an “uphill battle”reactions are an “uphill battle”

•• Energy must be put in to drive reactionEnergy must be put in to drive reaction

•• Energy for this comes from Energy for this comes from exergonicexergonic reactionsreactions

•• Must break down to build upMust break down to build up

Chemical EnergyChemical Energy

Potential energy

•• Actually, the same is true for Actually, the same is true for exergonicexergonic reactionsreactions

•• Energy input is required for the reaction to startEnergy input is required for the reaction to start

•• Otherwise reactions would be spontaneousOtherwise reactions would be spontaneous

•• Minimum energy required to overcome this energy Minimum energy required to overcome this energy barrier is known as barrier is known as activation energyactivation energy

EEaa = Activation= Activation

EnergyEnergy

Chemical EnergyChemical Energy

Potential energy

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•• Catalysts speed up chemical reactions without being Catalysts speed up chemical reactions without being used up in the reactionused up in the reaction

•• Reduce activation energyReduce activation energy

•• Can be used over and overCan be used over and over

•• EnzymesEnzymes are a class of proteins that act as catalystsare a class of proteins that act as catalysts

Chemical EnergyChemical Energy

Potential energy

•• Complete the concept map on page 2Complete the concept map on page 2--43 of your 43 of your study guidestudy guide

•• We will do a modified version of 2We will do a modified version of 2--4545

ActivityActivity