3. Heat Energy Absorption/Kinetic Energy
Increases
SUBLIMATION
FUSION VAPORIZATION
(MELTING) (BOILING)
SOLIDIFICATION CONDENSATION
(FREEZING) (LIQUIFYING)
DEPOSITION
HEAT ENERGY RELEASE/KINETIC ENERGY DECREASE
FIGURE 4.1. DIAGRAM OF ENERGY CHANGES
S
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D
G
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4. Legends:
1. Terms on the arrows are
processes that refer to the
changes.
2. An arrow indicates the direction
of phase change (e.g., from solid
to liquid)
5. Exercise:
A. Study the diagram in the
previous slide and determine
the relationships indicated by
the words and arrows.
6. B. Answer the following
questions.
1. What phase change
happens in the process of :
a) sublimation?____ to
______
7. b) fusion? _________to______
c) vaporization?_____ to_____
2. What happens to heat
energy during the phase
changes in number 1.
8. 3. What phase change
happens in the process of:
a) solidification?_____to____
b) Condensation _____to____
c) Deposition?_______to____
4. What happens to heat
9. energy during the phase changes
in number 3?
5. Which pairs of phase changes
happen in reverse?
a)_________and________
b)_________and________
c)____________and________
10. Adding energy to or heating a
solid increases the kinetic energy
of the particles until the solid
structure breaks down or
undergoes melting. The
temperature at which the solid
melts to form the liquid is called
11. the melting point. On the other
hand, removing heat from or
cooling a liquid decreases the
kinetic energy of the particles
until they are unable to move
and remain in fixed positions or
undergoes freezing. The tempe-
12. rature at which the liquid freezes
to form the solid is called the
freezing point.
Some of the liquid particles have
enough kinetic energy to
overcome the attractive forces
of their neighboring particles and
13. they are able to escape from the
surface of the liquid. This process
is called evaporation or
vaporization, since the particles
that escape enter the vapor or
gas phase above the liquid.
14. When a liquid is heated in an
open container, its vapor
pressure will rise until it equals
the pressure of the atmosphere
above the liquid. At this point,
the liquid will begin to boil and
the temperature at which this
15. Occurs is known as the boiling
point of the liquid. A liquid can
have any number of boiling
points, depending on the
pressure above the liquid.
16. Condensation, the reverse
process, also happens as
particles in the vapor phase are
cooled. Their kinetic energies are
lowered that they are attracted
back and returns to the liquid
phase.
17. Sublimation, is peculiar since the
solid phase passes directly into
the gas phase. Substances that
sublime have relatively high
vapor pressure(compared to the
atmospheric pressure), as well as
relatively weak forces of attrac-
18. tion between the particles of the
solid. Iodine (I2(s)), dry ice (CO2(s)),
and Naphthalene (C10H10) are
examples of substances that
sublime readily at room
temperature and pressure.
19. Deposition, the change from the
gas to solid phase without
passing the liquid phase, is the
reverse of sublimation. It is
demonstrated by Iodine crystals
being formed when iodine
vapors cool inside a beaker
20. covered with a watch glass.
Reverse phase changes occur at
the same temperature and if
they occur at the same rate, the
phase are said to coexist in
dynamic equilibrium.
