Keep Your
Candy Cool
With the
Power of
Evaporation!
Revised from http://www.sciencebuddies.org/sciencefair- projects/project_ideas/Chem_p076.shtml
Background
Question/Objective
Did you know that your body has a built-in cooler? And it might not be what you
think! Sweat is produced when you are hot, but its purpose is actually to cool your
body as the water in it evaporates from your skin. In this project, you'll use the
energy produced when water evaporates to cool down chocolate-covered candy
so it doesn't melt.
In this project, you will discover if you can use the evaporation of water to keep
chocolate-covered candy from melting.
Introduction to
experiment
You've probably noticed
that when you're outside
on a hot summer day,
your body starts to sweat.
But did you know that
sweat, or perspiration, is
actually your body's way
of cooling down? Sweat,
which is mostly water,
cools us down when it
evaporates.
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As water evaporates from an object, it makes the air above the object
more humid, (filled with more water vapor) which, in turn, slows down the
evaporation process. This is because once the air is already full of water vapor,
there is nowhere for the water on your skin to evaporate. But if you fan the moist,
humid air away, then the water can evaporate more quickly. That's why you feel
1
Evaporation is the
process that occurs when
Click here to watch a video clip from "Digit's Bwater changes from a
Day Surprise," the CYBERCHASE episode that
liquid into a gas (in this
inspired this project idea. Presented by
case, the gas is water
pbskidsgo.org.
vapor). When your sweat
evaporates, it carries heat energy from your body with it. The faster your sweat
evaporates, the more heat is carried away, and the more the skin surface from
which it evaporates is cooled.
cooler if you fan yourself or if there's a gust of wind.
In places with hot weather, engineers design misters—machines that spray a fine
water mist—for use in public places to help people keep cool. These misters help
out your body's natural sweat cooling system by providing more water to
evaporate and carry away heat energy from your body. Another way that you can
keep cool on a hot day is by dipping a bandana in water and wearing it around
your neck. The extra water from the bandana causes more evaporation, which
keeps your body even cooler than it would be with only sweat.
You can apply the same process of evaporative cooling that your body uses in
order to cool down objects. In the CYBERCHASE episode, "Digit's B-Day
Surprise,"(27 min) the CyberSquad must use evaporative cooling to keep Digit's
chocolate sculpture birthday present from melting while traveling through the
desert. Click on the video box above to watch the CyberSquad use the power of
evaporative cooling to save Digit's birthday present.
Procedure
1.
2.
3.
4.
5.
6.
7.
Each team member writes up their own hypothesis….they do
NOT have to be the same. Be sure to use IF and THEN.
Cut your paper towel sheet into strips that are about 4 cm wide.
Take one paper towel strip and wet it by dipping it into the bowl of water
and carefully wringing it out.
Keeping the candies in their foil wrappers, wrap one of the candies in the
wet paper towel strip and wrap another candy in a dry paper towel strip.
Place the two candies side-by-side beneath the lamp. Bend the lamp
down until the light bulb is 5 cm away from the candy.
a. If you don't have an adjustable-height lamp, prop the candies up
on a pile of books until they are within 5 cm of a 60-W light bulb
in a normal desk lamp.
Using your timer, time the candies for 10 minutes.
After 10 minutes, take the candies out from beneath the lamp. Remove
the paper towel strips and open the foil wrappers.
In your lab notebook, record your observations about what happened to
the candy wrapped in the wet paper towel versus the candy wrapped in
the dry paper towel.
2
Hypothesis
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Materials Needed
You can also watch this video clip from CYBERCHASE For Real to see how
Harry uses evaporative cooling to cool down on the tennis
court:http://pbskids.org/cyberchase/videos/harry-chills-out.
 Paper towel (3 sheets)--provided
 Scissors—in your tray
 Small bowl of room-temperature water-provided
 Chocolate-covered peppermint candies in foil wrappers (6)-provided
 Ruler-in your tray
 Desk lamp with adjustable height and 60-watt (W) light bulb. Note: If you
don't have an adjustable-height lamp, a normal desk lamp and a pile of
books can be used instead.--provided
 Timer--provided
 Lab notebook—each team member does their own
8. Repeat steps 1–7 two more times with new candies and paper towel
strips.
Data Table for
Observations
Graph
Make a copy of the following Data Table in your lab notebook and
complete.
Firmness:
Trial
#
1
2
Candy
#
1
2
3
Dry Wrap
Condition
A=no change
B= less firm
C=least firm(melted)
Wet Wrap
Condition
4
3
5
6
Graph
Need help?
Make a bar graph in your lab notebook using the data above. Use the
first two columns as your X axis and the Firmness as your Y axis.
Create a Graph
3
Composition Book
In your lab notebook, the summary is when you look at the data and
then use the data to answer your hypothesis. Your hypothesis will be
‘supported’ or ‘not supported’. Use the wording of your hypothesis in
your summary.
See rubric with this packet. Cut it out and glue it on the LEFT side of
your lab notebook. Be sure you have completed all the parts that you
received points on. Trade and check your team lab notebooks before
finishing in case one of the team forgot a part.
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Summary
Rubric (cut out and past on LEFT side of lab notebook page) Underlined words are the headings
for your lab notebook. Remember---only use RIGHT hand side of page—LEFT side of page is
used ONLY for the rubric. See sample lab notebook on counter if still have questions.
1.
2.
3.
4.
Time and date in upper right hand white area
Title of lab is centered on FIRST line
Question is written under title—left justified
Hypothesis is written under Question—left justified
and uses IF and THEN
Data table written on next page/filled out
5.
6.
6.
7.
8.
9.
Graph is constructed as per directions and data is
graphed
Summary is given and hypothesis is used as part
of the summary sentence.
Rubric is glued on LEFT side of notebook page.
Report is clean, no misspellings, neat.
TOTAL # of POINTS
Bonus Points Possible (2pt@): in your lab
notebook at the end of the lab, define the
following terms from this experiment.
Perspiration, evaporation, water vapor, humidity
Points
Possible
2
2
2
6
Points
Received
14
6
4
2
6
44
8
4
Description
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#