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This experiment uses hot water and cold water
to discover which makes ice form faster. Have your child create their
hypothesis either that cold water will form ice faster, or that hot water
will form ice faster.
For this experiment, you will need the
following materials:
Hot water
Cold water
2 Styrofoam cups or paper cups of the same size
To do the experiment you will need to label
one cup for cold water and one cup for hot water. Then fill the appropriate
cups, one with hot water and the other cup with cold water. Be sure that
each cup contains the same amount of water. Be sure to put a small
amount to water in the cups, or they will take too long to freeze.
You will then need to put both cups into the freezer at the same time. Go
back every 10-15 minutes to check the cups recording which one freezes
faster. You will leave the cups in the freezer until the following day,
when you will take them out and see if there are any differences in the ice
cubes.
Analyze the following:
If the ice cubes are the same size.
The differences in the ice cubes.
Which ice cube froze first?
After doing this project, you should
discover the following results:
Hot water will often freeze faster than
cold water. This is surprising to most people, even scientists. This
phenomenon is often called the
Mpemba effect. This however occurs only under certain conditions. And
includes a number of factors such as evaporation, convection, conduction and
supercooling.
One of the main factors is water freezing
is temperature. Water that is 90 degrees Fahrenheit is thought to have to
drop more in degrees in order to freeze than water that starts out at 70
degrees Fahrenheit. The water must drop in temperature until it reaches the
freezing point. Then it will stay at 32 degrees Fahrenheit or 0
degrees Celsius until the water solidifies. After the water turns to
ice, its temperature can become lower if the air temperature is lower.
Another factor is that of conduction.
Conduction is the process of cooling through the material that the water is
held in, for example, water held in a Styrofoam cup will be conducted
differently than water in a metal pan.
Evaporation is another factor that
contributes to the length of time the freezing of the water takes.
In addition to these factors, the following
factors may also contribute:
- The temperature of the
freezer
- The amount of water in
the container
- The size, shape and
material of the container
- Any type of air motion
over the water
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