EnergyEnergy

EnergyEnergy

The capacity to do some The capacity to do some kind of work.kind of work.

Involved when there is a Involved when there is a change in matterchange in matter–Chemical Chemical –PhysicalPhysical

Endothermic “Within-Endothermic “Within-Heating”Heating” Describes a process in which heat is Describes a process in which heat is

absorbedabsorbed from the environment. from the environment.

Feels ColdFeels Cold

Exothermic “Outside Exothermic “Outside Heating”Heating”

Describes a process in which heat is Describes a process in which heat is releasesreleases from the environment. from the environment.

Feels WarmFeels Warm

Examples•Ice melting•Water boiling•Cold Pack

Examples•Freezing water•Condensation•Explosion

Law of Conservation of Law of Conservation of EnergyEnergy

The law that The law that states that states that energy cannot be energy cannot be created or created or destroyed but can destroyed but can be changed from be changed from one form to one form to another.another.

HeatHeat The The energyenergy transferred transferred

between objects that between objects that are at different are at different temperaturestemperatures

Energy is always Energy is always transferred from transferred from higher-temperature higher-temperature objects objects to lower-to lower-temperaturetemperature objects objects until thermal until thermal equilibrium is reached. equilibrium is reached.

Kinetic EnergyKinetic Energy The energy of an object that The energy of an object that

is due to the object’s motion.is due to the object’s motion.

Potential Potential EnergyEnergy The energy The energy

stored within a stored within a physical system.physical system.

TemperatureTemperature A measure of the average kinetic energy of the particles in an A measure of the average kinetic energy of the particles in an

object.object. A measure of how hot (or cold) something is.A measure of how hot (or cold) something is. Not dependent on the size orNot dependent on the size or

type of object.type of object. Not energyNot energy Measurement of energyMeasurement of energy

Temperature ScalesTemperature Scales

Fahrenheit (not used in chemistry)Fahrenheit (not used in chemistry) Celsius Celsius

– 00°C Water Freezes°C Water Freezes– 101000°C Water Boils°C Water Boils

SI unit KelvinSI unit Kelvin– Absolute zero (0 K)-minimum/zero average kinetic Absolute zero (0 K)-minimum/zero average kinetic

energy of all particles energy of all particles

Temperature ConversionTemperature Conversion

t (t (°C) = T (K) – 273.15 K°C) = T (K) – 273.15 K T (K) = T (K) = t (t (°C) + 273.15 °C °C) + 273.15 °C PracticePractice

0 °C0 °C

50 K50 K120 °C 120 °C 1000 K1000 K

O °C + 273.15 = 273.15 KO °C + 273.15 = 273.15 K

12O °C + 273.15 = 393.15 K12O °C + 273.15 = 393.15 K50 K – 273.15 K = -223.15 °C50 K – 273.15 K = -223.15 °C

1000 K – 273.15 K = 726.85°C1000 K – 273.15 K = 726.85°C

Transfer of HeatTransfer of Heat May not affect the temperatureMay not affect the temperature Phase ChangesPhase Changes

– Solid/LiquidSolid/Liquid– Liquid/GasLiquid/Gas

Affects Substances DifferentlyAffects Substances Differently– IronIron– WaterWater

Specific HeatSpecific Heat– The quantity of heat required to raise a The quantity of heat required to raise a

unit mass of homogeneous material 1 K unit mass of homogeneous material 1 K or 1or 1°C in a specified way given constant °C in a specified way given constant pressure and volume.pressure and volume.

Heating Curve for Heating Curve for WaterWater

http://coolcosmos.ipac.caltech.edu/cosmic_classroom/light_lessons/thermal/measure.html