I CA N :
- CON ST RUC T A G R A PH T HAT R E P R ESENTS P HA S E CHA N G ES R E P RESENTED BY
T HE T E MPERATURE OF A SA MP LE VS . T HE T I ME I T HA S BE E N HEAT ED.
- DI F F E RENTIATE BE T WEEN A P HA S E CHA N G E AN D A T E MPERATURE CHAN G E
( OBS E RV ING T HE PAT TERN ON T HE G R A P H ).
- E X P LA IN WHY I T I S A P HA S E OR T E M PERATU RE CHA N G E .
- R ECOG N IZE T HAT DUR I N G T HE P HA SE CHA N G E T HE E N ERGY G OES I N TO
CHA N G ING T HE P OS I TION OF T HE PA RT ICL ES ( W HI CH I S P OT E NTIAL E N E RG Y)
I N STEA D OF CHA N G I NG T HE KI N E TIC E N E RGY ( WHI CH I S T HE T E MPER ATURE ) .
- R ECA L L T HAT T HE K I N E TIC E N ERGY OF T HE PA RT ICL ES I S U S E D TO BR EA K T HE
AT T R AC TI VE FORCES BE T W E EN T HE PA RT I CLES.
- R ECOG N IZE T HAT A S UBSTANCE ME LTS OR BOI L S DE P E NDI NG ON T HE K I N E TIC
E N E RGY A S PA RT OF T HE P HA S E CHA N G E ( A N D CON V E RSELY WHE N COOL I N G ) .
- E VA LUATE T HE DI R EC T ION OF E N E RGY F LOW A N D I DE N TIF Y R EAC T IONS A S
E N DOT HERMIC VS . E XOT HERMI C.
- R E L ATE T HAT I N G E N ERAL T HE S PACE BE T W E EN T HE PA RTI CLES DE T ERMI NES
T HE P HA S E OF T HE M AT T ER ( UN DE RSTA NDING WAT E R I S A N E XCE PTION) .

Fire at Lima Factory 10/2014

Kinetic Theory
• All matter is made of atoms and molecules that act like tiny particles
• The particles are always in motion. (Higher temp=faster movement)
• At same temp, heavier particles move slower the lighter particles.

Solids have definite shape and volume
• Solids do not need containers
• Particles cannot change position
• Two categories
◦ crystalline-iron, diamonds, ice
◦ amorphous-rubber, wax, gum
(can be compressed)

Liquids can change shape, not volume!
• Particles can slid past each other.
• Move fast enough to overcome force of attraction between them. (flow freely)
• Take shape of container
• Surface tension: force acting on the particles at the surface of a liquid that causes liquid to form spherical drops.

Gases are free to spread in all directions
• Gas expands to fill space
• He can travel at 1200 m/s
• One cylinder of helium can fill 700 balloons, but the cylinder is to the volume of 5 inflated balloons.
• Gases change shape and volume

Plasma is the most commons state of matter.
• 99% of all known matter in the universe
(sun/stars) is plasma.
• Does not have definite shape
• Plasma: state of matter that starts as gas and then becomes ionized (turn atoms into ions)
• Similar to gas, but conducts electricity.
• Ex on earth: lightning, fires, northern lights
(electric current through gas)

Energy’s Role
• Energy: the capacity to do work
• Ex: candles for light, batteries, electricity, food we eat, chem. Reactions that release heat.
• Particles in motion (solid, liquid, gas) have kinetic energy.
• Thermal Energy: the total kinetic energy of the particles that make up an object.
• Higher temper  faster moving particles  more kinetic energy  more thermal energy.
• May also depend on number of particles.
• In the previous slide, which picture shows most thermal energy?

How do we measure temperature?
• Hot or cold?
• Temp is the measure of how the average kinetic energy of the particles in an object.
• Temp of a substance is not determined by amount.
• Total kinetic energy is determined by amount.
• Tea pot example.

Energy and Changes of State
• Water can be ice, liquid, gas. Still H20
• Energy is different in each.
• Temperature is a measure of energy
• Transfer of energy known as heat causes change of state.

Some changes of state require energy
(heating up)
• Melting, requires energy (heating up)= endothermic change.
• Melting point: water 0 degrees C, Table salt is 801 degrees C
• Evaporation: The change of a substance from a liquid to gas
• Boiling Point: water is 100 degrees C, Mercury is 357 degrees C.
• Reversing the process is exothermic…
• Think about the energy transferring when you sweat.
• Sublimation: the process in which a solid changes directly into gas.
• Common in dry ice, or ice left in freezer for a long time.
• https://www.youtube.com/watch?v=_jvicQ2Xj0o

Energy is released in some changes of state (cooling down)
Condensation: the change of a substance from a gas to a liquid
◦ Energy is released from water to its surroundings.
◦ Condensation point: temp at which gas becomes liquid.
◦ Freezing point: temp in which liquid becomes solid.
Condensation and freezing are both exothermic reactions because energy is released.

Thanks Aja’s boyfriend… <3 https://www.youtube.com/watch?v=5T68TvdoSbI

Conservation of Mass and Energy
In both physical and Chemical changes, total mass of matter stays the same before and after the change.
Law of conservation of mass: mass can neither be created nor destroyed.
◦ Does burning a match lose mass?
◦ There is mass in oxygen. (ash, smoke, and gases= original mass)
Law of conservation of energy: energy can be converted to different forms, but never created nor destroyed.
◦ Burning gas produces energy need to move car.