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Krampf #481 How Heat Patches Work
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KRA-@aol.com
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Apr 03, 2007 23:51 PDT
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Robert Krampf's Experiment of the Week
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The new Science Experiment video is up. This week, we see how you can
predict how many sections are in an orange before you slice it.
You can see the video and text versions of this experiment at:
http://www.krampf.com/experiment_vid.html
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After we donated the FCAT DVDs to every public school in Florida, we have
about 300 left over copies. They have a short, donated by message at the start.
While the DVD would normally sell for $29.95, we are offering these left over
DVDs for a discounted price of $17.95. For those of you on the Experiment of
the Week list, we have further reduced of $14.95. If you would like
information on how to purchase a copy, send an email to: Travelin-@aol.com.
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This Week's Experiment - #481 How Heat Patches Work
Greetings from our home in Jacksonville, Florida. It has been another great
week of working on videos, playing in the garden, and taking photos. We also
took a trip to Ginny Springs, for a day of swimming, tubing and photography.
I was especially pleased with some photos of the water snakes that were
sunning and swimming in the springs. Nancy was especially pleased when the snakes
moved on, so she could enjoy the water.
In this week's experiment, we will see how the heat patches sold for treating
muscle soreness work. Nancy recently used these to help with a sore back,
the result of her ambitious gardening. They work great, and I immediately
wanted to know how they work.
To find out, you will need:
a jar with a lid
a thermometer (I got a cheap at the $1 store)
steel wool
vinegar
a bowl
First, put the therrthermometer into the jar and put on the lid. Let the jar
sit for about 15 minutes and then check the temperature. Write that down.
Next, place the steel wool into a small bowl. Pour some vinegar onto it,
using enough to get the steel wool very wet. Squish it around a bit and then
squeeze out as much vinegar as you can. Put the wet steel wool into the jar, up
against the thermometer. Again, note the temperature and write it down. Put
the top on the jar and leave it for five minutes.
After five minutes, check the temperature again. It should have risen. When
I tried this, it had risen by 10 degrees, but your results may differ. Put
the lid back on the jar and wait another 10 minutes. Check the temperature
again. Then wait another 10 minutes and check again. Each time, the temperature
rises. When I tried it, the temperature rose more than 20 degrees.
Look at the steel wool. You should notice that it has changed color. It
started as a steel gray, but now it is a reddish rust color. That is an
appropriate description of the color, since the steel really has rusted.
Understanding the Science
Why did the temperature go up? The key is to notice what else happened. The
steel wool rusted. Rust is the result when steel or iron combine with oxygen
from the air in the presence of water or some other liquid that conducts
electricity. During the rusting process, heat energy is released.
OK, so why did we wet the steel wool with vinegar? The steel wool has a very
thin coating of oil. Oil separates the steel from the oxygen in the air to
keep it from rusting. Vinegar removes the oil, letting the rusting process
begin. The vinegar also works better than water, speeding up the rusting
process.
If you read the ingredients on the heat patches, you will find that the main
ingredient is iron powder. Iron, like steel, will combine with oxygen to form
rust. The iron powder has not been coated with oil, so it has to be stored
in an airtight package. As long as no oxygen can get to the powder, it cannot
not rust. Once you open the package, air and water vapor enter and begin to
react with the iron to form rust. It also begins to give off heat. Once the
reaction is complete, the patch will stop giving off heat. Then you can use
scissors to open it. Inside you will find a lot of rust, the remains of the
iron powder.
This science experiment has been around for a LONG time. I first performed
it when I was about 12 years old, and it was already a classic by then. I
celebrated my 50th birthday last September, so you can do the math and see how
long it has been. Still, it was only recently that someone was smart enough to
turn a simple science experiment into a way to help people with sore backs, and
along the way, probably make a lot of money. It just goes to show you that
there are still plenty of discoveries to be made, and plenty of ideas just
waiting for someone to notice them.
Have a wonder-filled week!
Robert Krampf
Robert Krampf's Science Education Company
www.krampf.com
Who is Robert Krampf?
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