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Unit 13: Thermodynamics Page 16
water molecules get close to the temperature drops and the
something cool, they will combine molecules continue to slow, the
and turn from gaseous to liquid bonds between the molecules can
state. pull them together tighter and
tighter.
This is what happens to your
bathroom mirror during a shower Eventually the molecules will fall
or bath. The gaseous water into a matrix, a pattern, and stick
molecules that are having fun together quite tightly. This would
bouncing and jiggling around the be the solid state. The act of
bathroom get close to the mirror. changing from a liquid to a solid is
The mirror is colder than the air. called freezing and the
As the gas molecules get close temperature at which it changes is
they slow down due to loss of called (say it with me now)
temperature. If they slow enough, freezing point.
they form loosey goosey bonds
Think about this for a second - is
with other gas molecules and
the freezing point and melting
change from gas to liquid state.
point of an object at the same
The act of changing from gas to temperature? Does something go
liquid is called condensation. The from solid to liquid or from liquid to
temperature at which molecules solid at the same temperature?
change from a gas to a liquid is
If you said yes, you’re right! The
called the condensation point.
freezing point of water and the
Clouds are made of hundreds of
melting point of water are both 32°
billions of tiny little droplets of
F or 0° C. The temperature is the
liquid water that have condensed
same. It just depends on whether
onto particles of some sort of dust.
it is getting hotter or colder as to
whether the water is freezing or
melting.
The boiling and condensation point
is also the same point. Now I’m
going to mess things up a little bit.
Substances can change state at
temperatures other than their
different freezing or boiling points.
Many liquids change from liquid to
Now let’s turn the heat down a bit
gas and from gas to liquid
more and see what happens. As
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