Changing State
Pearson Science SB 7
Section 2.3
Pages 56-59
Adding Heat
Given enough heat, solids will change
into liquids and liquids will change into
gas.
Processes that involve addition of
heat:
Melting
Evaporation
Boiling
Sublimation
Melting
Melting is the process in which adding heat
causes a solid to change into a liquid.
The substance remains the same
substance- physical properties change
Heat adds energy to particles causing them
to vibrate faster
Particles around edges are first to vibrate
enough to break free
Melting Point
The temperature at which a solid melts
A substance is solid below its melting point
and liquid above the melting point
Water’s melting point = 0˚ C
Different substances have different melting
points
Melting Ice Animation
Evaporation
The process in which heat causes a liquid
to change into a gas.
Also known as vaporization.
Adding enough heat/energy allows particles
near the surface to move fast enough to
break away and escape as gas.
Evaporation Animation
Boiling
A special case of evaporation.
Evaporation occurs at any temperature, but
boiling only happens at the boiling point.
Bubbles form and rise to surface to escape as
gas.
The boiling point is the temperature at which a
liquid changes to a gas. It represents the
highest temperature at which a substance is
liquid and the lowest temperature at which it is
gas.
Water: BP = 100˚ C
Boiling Animation
Sublimation
The process in which heat causes a solid to
change directly into a gas.
Examples: Iodine and solid carbon dioxide
(dry ice)
http://www.media.pearson.com.au/schools/
cw/au_sch_lewis_cw1/int/sublimation/f11/1
108.html
Removing Heat
A substance can change state if enough
heat is removed from it.
Processes involving removal of heat:
Freezing
Condensation
Deposition
Freezing
Also known as solidification.
Occurs when heat is lost and a liquid
changes into a solid.
As it cools, liquid loses energy from its
particles so they slow down, vibrate on the
spot, and form bonds between particles
Water Freezing- Ice Bomb
http://www.middleschoolchemistry.com/mult
imedia/chapter2/lesson4#ice_bomb
Freezing Point
The temperature at which a liquid changes
to a solid.
Freezing is opposite process of melting, so
occurs at same temperature.
Water: FP = 0˚ C
Condensation
When a substance loses heat and changes
from gas into liquid.
As gas cools, particles slow down until they
form bonds and liquid droplets
Deposition
Some gases change directly into solids
without going through liquid state.
States of Matter Video and
Song
http://teacher.scholastic.com/activities/stud
yjams/matter_states/
Role Play
P. 59