Solids, Liquids, & Gases
Chapter 3
Changes of State
 Changes between solid & liquid
- particles of a liquid have more thermal (kinetic) energy
than particles of a solid
-MELTING
-particles of a solid speed up and break free becoming a
liquid
-energy is gained in the process = endothermic reaction
-FREEZING
-particles of a liquid slow down to become a solid
-energy is lost in the process = exothermic reaction
Changes Between Solid and Liquid
The change in state from a solid to a liquid
is called melting.
Changes Between Solid and Liquid
The change of state from liquid to solid is
called freezing.
 Changes between liquid & gas
-particles of a gas have more thermal (kinetic) energy than
particles of a liquid
-VAPORIZATION
-evaporation
-boiling – the boiling point of a substance depends
on the air pressure above it, the greater the air
pressure the higher the boiling point
sea level = 100°celsius
1,600 meters = 95°celsius
-CONDENSATION – when particles in a gas lose enough
thermal energy to become a liquid
-when warm water vapors reach a cooler surface the
water vapor condenses into liquid droplets
 Changes between solid and gas
-Sublimation- particles of a solid do not pass through the
liquid state to form a gas
Temperature and Changes of State
A beaker of ice at –10ºC
was slowly heated to
110ºC. The changes in
the temperature of the
water over time were
recorded. The data were
plotted on the graph
shown here.
Temperature and Changes of State
Reading Graphs:
What two variables are
plotted on the graph?
Temperature (ºC) on the yaxis, time (minutes) on the xaxis
Temperature and Changes of State
Reading Graphs:
What is happening to
the temperature of the
water during segment C of
the graph?
The temperature is
rising from 0ºC to 100ºC.
Temperature and Changes of State
Interpreting Data:
What does the
temperature value for
segment B represent? For
segment D?
Segment B: melting
point of ice; segment D:
boiling point of water
Temperature and Changes of State
Drawing Conclusions:
What change of state is
occurring during segment B of
the graph? For segment D?
Change from solid to liquid;
change from liquid to gas
Temperature and Changes of State
Inferring:
In which segment, A or E,
do the water molecules have
more thermal energy? Explain
your reasoning.
Water molecules in
segment E have more
thermal energy because they
are at a higher temperature.