Matter and Phase Changes
Matter
Law of Conservation of Mass/Matter

Matter cannot be created or destroyed in an
ordinary chemical reaction just rearranged to form
different substances
Types of Properties
PROPERTIES
PHYSICAL
INTENSIVE
CHEMICAL
EXTENSIVE
Kinetic Theory
All matter is made of tiny particles in constant
motion.
Potential Energy (PE)


energy due to the position or condition
at the atomic level:
 the distance between the particles
 closer= lower PE
farther = higher PE
Kinetic Energy (KE)

energy due to motion
 Faster=higher KE
slower= lower KE
Phases of Matter
State
or
Phase
Particle
level
picture
Particles
description
Keep
Keep
Volume? shape
?
Solid
Arranged in
orderly pattern
Yes
Yes
Liquid
Touching, but not
tightly packed
Yes
No
Gas
Far apart and
rarely touching
No
No
Phases of Matter
State
or
Phase
Particle
Movement
Solid
Vibrational
only
Very
Low
Low
Ice
Liquid
Vibrational &
translational
Low
Moderate
Water
Move freely
High
High
Vapor
Gas
Amount PE
Amount KE Example
Plasma
extraordinary state of matter
consists of high energy particles
electrons are stripped from their nuclei
examples:



fluorescent light
Stars
Lightning
*Most Abundant State of Matter in the Universe!*
Phase Changes
Changes of State
Adding or removing energy (heat) to a
substance causes phase changes
The potential energy of the particles is
increased or decreased
During a phase change, temperature
does NOT change
Phase Changes
Melting

S changes to L
(adding energy)
Freezing


L changes to S
(removing energy)
Melting point & freezing point of a substance
occur at the same temperature.
Phase Changes
Boiling

L becomes G
(adding energy)
Evaporation

L becomes G
(adding energy)
Condensation

G becomes L
(removing energy)
Difference between boiling & evaporation:
 Boilinga specific temp. below the surface
 Evaporation any temp. at the surface
Phase Changes
Deposition

G becomes S (removing energy)
 Examples: Snow, frost
Sublimation

S becomes G
(adding energy)
 Examples: solid CO2 (dry ice), solid air fresheners
Phase Change Graphs (T vs t)
Melting
AB
-heat Δ KE
-move faster
-temp. 
-solid
BC
-heat Δ PE
-get farther apart
-temp. stay same
-melting
CD
-heat Δ KE
-move faster
-temp. 
-liquid
Phase Change Graph (T vs t)
Boiling
DE
-heat Δ PE
-get farther apart
-temp. stay same
-boiling
EF
-heat Δ KE
-move faster
-temp. 
-gas
Phase
Change
Graph
(T
vs
t)
A
C
B
E
D
F
AB
BC
CD
-KE 
-PE 
-KE 
-slows down
-closer together
-slows down
-temp. 
-temp. stays same
-temp. 
-Gas
-Condensation
-Liquid
Phase Change Graph (T vs t)
A
B
C
D
E
F
DE
EF
-PE 
-KE 
-closer together
-slows down
-temp. stays same
-temp. 
-Freezing
-Solid
Phase Change Graph (T vs t)
Boiling
Point
Boiling
Freezing
Point &
Melting
Point
Freezing
Melting
What is the boiling point?
What is the melting
point?
What is the freezing
point?
Phase Change Graph (T vs t)
If melting & freezing points occur
at the same temperature, how do
you know which change is
occurring?
-depends on whether adding or
removing energy
Phase Change Graph (T vs t)
What is this substance?
-Water
How do you know?
-Boiling & melting & freezing
points of water (Intensive
properties)
Classification of Matter
Matter
Pure Substances
Elements
Compounds
Mixtures
Homogeneous
Heterogeneous
Heat
Endothermic
Solute and solvent particles break
attractive forces holding them together
Exothermic
When solute and solvent particles mix,
particles now attract each other
Solubility
Refers to the maximum amount of
solute that will dissolve in a given
amount of solvent at a specified
temperature and pressure.
g solute / 100 g solvent
Saturated vs Unsaturated vs
Supersaturated