Download Phases of Matter and Phase Changes

Phases of Matter, Energy
and Phase Changes
Phase of Matter

.
Depends on
strength of forces
of attraction
between particles.
Solids

Definite shape and volume.
Most dense phase (Exception is water!)
Difficult to compress.
Particles vibrate in fixed positions
Crystalline lattice structure.
Most attraction between particles.

Note:






Amorphous solids include glass,
plastic, wax, and silly putty
Liquids





Definite volume
No definite shape
Hard to compress
Particles slide past each
other
Forces of attraction
between particles still high
Gases





No definite shape or volume
Expands to fill container
Lowest density
Little attraction between
particles
“Vapor” = a gaseous state of
something that is normally liquid

(Ex: water vapor)
Changes in Phase
Gas
Condensation
Vaporization
(Boiling or Evaporating)
Liquid
Solidification
Melting (fusion)
Solid
Phase Changes
Short Summary video on phases: (1 min)
http://www.youtube.com/watch?v=s-KvoVzukHo&safe=active
Applet: (Excellent)
https://phet.colorado.edu/en/simulation/states-of-matter
http://www.harcourtschool.com/activity/states_of_matter/
Let’s Skip a Phase

Sublimation

Directly from the solid
phase to the gas phase.

Happens with substances
with weak intermolecular
forces of attraction

They separate easily!

Ex: CO2(s) dry ice, Iodine
CO2(s) → CO2 (g)
http://www.youtube.com/watch?v=8tHOVVgGkpk
Energy

Energy = capacity to do work or produce heat.
It can be anything that causes matter to move or
change direction.



Many different types of energy
Ex: electrical, thermal, atomic, mechanical
“Chemical” energy is the potential energy stored in
the bonds between atoms
Law of Conservation of Energy

Energy can’t be
created or
destroyed, just
transferred from
one form to another
PE vs. KE

Potential Energy
stored energy


Energy can be stored in
bonds between atoms
Kinetic Energy
energy of motion

All atoms are moving
and vibrating unless at
absolute zero
Energy and Changes to Matter

Exothermic Change:


A + B → C + D + energy
Energy is released or “ex”its
Endothermic Change: A + B + energy → C + D

Energy is absorbed or “en”ters
Energy During Phase Changes

Solid
Liquid or Liquid
Gas
Endothermic
 Energy is absorbed and overcomes attractive
forces between particles

Add heat

Gas
Liquid, Liquid
Solid
Exothermic
 As particles come closer together energy is
released

Remove heat
Heat Energy

Also called Thermal energy, it makes particles
move more as it is added

Measured in Joules or calories.
http://www.youtube.com/watch?v=f1eAOygDP5s&safe=active
Heat Flow or Transfer

Heat energy
travels from an
object of higher
temp. to one of
lower temp. until
both reach the
same temp.
Temperature

Measure of the average kinetic energy
(motion) of all the particles in a sample.

Not a form of energy!!!

But if you add heat energy or take it away, it
causes particles to move faster or slower and
thus changes the temp.
Heat vs Temp.
https://www.youtube.com/watch?v=yxBTE
MnrZZk
Heat vs. Temperature

Teacup vs. Bathtub

Both at 25˚C

Which one contains
more heat energy?

Which one has the
greater average KE?
Temperature Scales Used in
Chemistry
Celsius
 Fixed points of scale based on the freezing
point and boiling point of water

0 °C = water freezes, 100 °C = water boils
Kelvin
 Scale based on lowest temperature possible

0 K = absolute zero
https://www.youtube.com/watch?v=-G9FdNqUVBQ
Temperature
Scales and
Conversions
K = ˚C + 273
Absolute Zero

Temperature at which particles have
slowed down so much they no longer
possess any kinetic energy.
0 Kelvin
-273° Celsius
Heating & Cooling Curves

Graphically represents temp. changes as heat
energy is added or taken away.
Label This Graph
Interpreting the Graph

The slanted portions =
temp is changing


Single phase is heating
up or cooling down
KE is changing

The flat portions =
temp not changing


Substance undergoing
a phase change
PE is changing
Heating Curve for Water
Label Melting Pt? Boiling Pt?