Physical Science

Heat and Matter

MatterMatter

Anything that occupies space and has mass

Ex. AirLaw of Conservation of Matter

Matter is neither created or destroyed

It is only changed from one form to another

Solid, liquid, gas, and plasma are states or phases of matter

Kinetic Molecular Theory

All matter is made up of tiny atoms and molecules that interact physicallyMolecules are separated by empty spaceAll molecules are in constant motion (kinetic energy)Kinetic energy increases as heat is added and decreases as heat is removed

Phases of Matter - Solids

Definite shape and volume

Rigid 3-D structure

Atoms/molecules bonded in place

Allowed motions restricted to vibration in place only

Phases of Matter - Liquids

Definite volume, indefinite shape

Only weak cohesive bonds between component molecules

Constituent molecules mostly in contact

Allowed motionsVibrationRotation

Phases of Matter - Gases

Indefinite volume and shapeMolecules mostly not in contact Allowed motions

Vibration and rotation (molecules with more than one atom)

Random, mostly free paths

Phases of Matter - Plasma

PlasmaA very hot gas consisting of atoms that have been stripped of their electrons because of high kinetic energies

For a picture, see the link belowhttp://www.rialian.com/rnboyd/plasma2.jpg

Phase ChangesSolid/liquid

Liquid/gas

Solid/gas

Temperature(Direction ->)

Melting Boiling Sublimation

Temperature(Direction <-)

Freezing Condensation

Sublimation

Evaporation and Condensation

Individual molecules can change phase any time

Evaporation:Energy required to

overcome phase cohesionHigher energy molecules

near the surface can then escape

Condensation: Gas molecules near the

surface lose KE to liquid molecules and merge

HeatA form of energy transfer

between two objectsEnergy always moves from

higher temperature regions to lower temperature regions

Calorie (cal) – unit of energy needed to raise temperature of 1 g of water 1 degree Celsius

TemperatureA measure of the internal energy of an object

ThermometersUsed to measure temperature

Temperature measured in degrees2 temperature scales

Celsius: water freezes at 00 and boils at 1000 Fahrenheit: water freezes at 320 boils at 2120

WaterMajor constituent of living things“Universal solvent”Dissolves most moleculesSolid phase less dense than liquid

Ice floats!High specific heat

Amount of heat (energy) needed to increase the temperature of 1 gram of water 1 degree Celsius

Cohesion Attractive forces between like molecules

Adhesion Attractive forces between unlike molecules

http://www.physicalgeography.net/fundamentals/8a.html

http://www.uni.edu/~iowawet/H2OProperties.html

Heat flow Three mechanisms for heat

transfer due to a temperature difference

1. Conduction2. Convection3. Radiation

Natural flow is always from higher temperature regions to cooler ones

ConductionHeat flowing through

matter (solids)Mechanism

Hotter atoms collide with cooler ones, transferring some of their energy

Direct physical contact required; cannot occur in a vacuum

Poor conductors = insulators (Styrofoam, wool, air…)

Convection Energy transfer

through the bulk motion of hot material (liquids and gases)

ExamplesSpace heaterGas furnace

(forced)Natural convection

mechanism - “hot air rises”

Radiation Radiant energy - energy associated with

electromagnetic wavesCan operate through a vacuum All objects emit and absorb radiationTemperature determines

Emission rateIntensity of emitted lightType of radiation given off

Temperature determined by balance between rates of emission and absorptionExample: Global warming

Study Websites What Is Matter?: Properties and Classification of

Matter http://www.learner.org/resources/series200.html#

The Particle Nature of Matter: Solids, Liquids, and Gases http://www.learner.org/resources/series200.html#

Physical Changes and Conservation of Matter http://www.learner.org/resources/series200.html#

Chemical Changes and Conservation of Matter http://www.learner.org/resources/series200.html#

Density and Pressurehttp://www.learner.org/resources/series200.html#

Rising and Sinking http://www.learner.org/resources/series200.html#

Water Propertieshttp://www.uni.edu/~iowawet/H2OProperties.html

Heat and Temperature http://www.uni.edu/~iowawet/H2OProperties.html

GACE II Information- ECE/MG

Water Freezing point

Kinetic energy of molecules reduced enough to allow crystallization

Presence of solute particles interferes with crystal formation lowers the freezing point (freezing point depression)

Example: Salt excluded from ice as seawater freezesIce is practically pure waterSalinity of seawater increases

Example: Antifreeze, ethylene glycolBoiling point

Normal boiling pointTemperature where vapor pressure = average sea level

atmospheric pressureVapor pressure over a solution less than that of the pure

solventSolute particles displace solvent particles on surface,

hindering vaporization Leads to higher boiling point

GACE II Information- MGInterpreting Diagrams that Illustrate Changes in the Physical States of Matterhttp://dthschemistry.com/ch_12%20Phase%20Diagrams.doc