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"I sent CoolStuff to a new teacher I'm
mentoring. I use CoolStuff all the time and love it. The kids love it and learn from it!"
~ Dixie D. from Texas
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Lab #23.4
Heat: Cooling by Boiling
Purpose
In this activity, students will
see that water will boil when
pressure is lowered.
Discussion
Whereas evaporation is a change
of phase from liquid to gas at
the surface of a liquid, boiling
is a rapid change of phase at
and below the surface of a
liquid. The temperature at which
water boils depends on
atmospheric pressure. Have you
ever noticed that water reaches
its boiling point in a shorter
time when camping up in the
mountains? And have you noticed
that at high altitude it takes
longer to cook potatoes or other
food in boiling water? That’s
because water boils at a lower
temperature when the pressure of
the atmosphere on its surface is
reduced. Let’s see!
Required
Equipment
400-mL beaker,
thermometer, vacuum pump with
bell jar
Download
Student Worksheet
Teacher Notes
Return to Lab Menu
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Bell Jar |
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