1. Tying up loose ends:
Behavior of Gases
Jumping Phase
Evaporation is cooling

2. Endothermic vs. Exothermic
• Anything Endothermic involves
heat/energy entering the
reaction/change
• Anything Exothermic involves
heat/energy exiting the
reaction/change

3. So….. what’s so special
about Gases?
• What do gases do when they heat up?
– Who can explain it?? (for a ticket!)
• What do gases do when they cool down?
– Who can explain it?? (for a ticket!)
• What makes a hot air balloon rise?
– Who can explain it?? (for a ticket!)
• What would happen to a regular balloon if I
blew it up and put it in the freezer?
– Who can explain it?? (for a ticket!)

4. Jumping Phase!!!!
• Sublimation
– ENDOTHERMIC!!
– Going from a solid
to a gas- it skips
the liquid phase
altogether.
– SO much energy
is added that it
goes straight to
the last phase!
– EX: Dry Ice
• Deposition
– EXOTHERMIC!!!!
– Going from a gas
straight to a solidit skips the liquid
phase altogether!
– SO much energy
is taken away that
it goes straight to
the last phase!
– EX: Snow!

5. Evaporation cools!
• What did you learn from the
Evaporation lab last week?
– Evaporation is a cooling process!
– As the liquid evaporates and becomes
a gas, it has to get it’s energy from
somewhere. So where does it get it
from?

6. Evaporation cools!
• Which of the liquids cooled the
fastest?
– Why do you think?
– What does it have to do with density?

7. Evaporation cools!
• Why do we sweat when we work
out?
– Why would our bodies do this?
– What is the point?

8. Sublimation Lab
• What did we learn yesterday?
– Why was the CO2 white at first when
it was coming off of the dry ice?
– Was the CO2 more or less dense then
air? How do you know?
– Why did the dry ice sublimate faster
in water than air?
– And why was it faster in alcohol than
water?