PHASE CHANGES

1
PHASE CHANGES
Moving from one state of matter to another
Always think in terms of thermal energy
Thermal energy total energy of a substances
particles due to their movement or vibration
Bill Howard Hopkinton Middle School
2
MELTING
solid
liquid
Thermal energy is increased
Molecules speed up
3
Melting point is a characteristic property of a
substance
Water 00C
Steel 13700C
4
FREEZING
solid
liquid
Thermal energy is decreased
Molecules slow down
5
Freezing point is a characteristic property of a
substance
Freezing Point Melting Point
Water 00C
Steel 13700C
6
EVAPORATION
gas
liquid
Occurs at any temperature above the freezing
point but rate increases with rise in temperature
Occurs at surface only
A type of vaporization
7
Fast evaporation rate
HOT
COLD
S-l-o-w evaporation rate
8
EVAP0RATION
No additional thermal energy is needed for
evaporation to take place
gas forms
Some individual molecules have more than the
average energy
Gas forms at the surface only
Enough energy to escape the liquid
9
BOILING
gas
liquid
Increase in thermal energy
Bubbles form
Gas forms at surface and in the liquid
A type of vaporization
10
Boiling point is a characteristic property of a
substance
Water boils at 1000 C
Propane boils at -42.10 C
11
BOILING
Additional thermal energy is needed heat
or pressure
Gas forms at the surface
Gas forms within the liquid
12
VAPORIZATION
liquid
gas
DRAMATIC increase in thermal energy
RAPID gas production
13
Molten lava entering the sea
14
CONDENSATION
gas
liquid
Thermal energy is decreased
Molecules slow down
15
Dew on a spider web
16
SUBLIMATION
solid
gas
SKIPS THE LIQUID PHASE
17
Snow and ice slowly sublime even when the
temperature is below 00 C
Mothballs
Frozen CO2 doesn't melt.
18
DEPOSITION
solid
gas
SKIPS THE LIQUID PHASE
19
FROST
20
Are these physical or chemical changes? Why?
Physical Changes
Only the movement of the molecules is changing
Changes are reversible
No new substances are formed
21
Phase Changes
GAS
TYPES OF VAPORIZATION
boiling
evaporation
vaporization
condensation
no bubbles
bubbles
fast bubbles
LIQUID
sublimation
deposition
melting
freezing
SOLID
22
Work Cited
http//www.runningdogbronze.co.uk/grafix/storypix/
actual/melting.jpg
http//www.zonalibre.org/blog/leopantomimo/archive
s/ice_cube.jpg
http//www.nd.edu/rroeder/ame466/fieldtrip/1604.J
PG
http//www.bahiker.com/pictures/northbay/palomarin
/websize/023ice.jpg
http//www.cartoonstock.com/newscartoons/cartoonis
ts/ksc/lowres/kscn731l.jpg
http//www.marinemkt.com/media/graphics_OO/inpot.j
pg
http//www.npga.org/i4a/pages/index.cfm?pageid636

http//www.harcourtschool.com/glossary/science/def
ine_spn/gr1/evapo1d.html
http//www.elmhurst.edu/chm/vchembook/163boilingp
t.html
http//www.cyrtaliade.de/private/travel/hi1/day03.
html
http//www.weatherquestions.com/condensation.gif
http//www.carleton.ca/tpatters/teaching/climatec
hange/solar/mars6.html
http//www.ashland-city.k12.oh.us/ahs/classes/hort
/2001/dec10/grasses.jpg
http//www2.helsinginsanomat.fi/kuvat/uutiset/2003
/09/04/20030904ie02i.jpg