"... heat cells are the part of ThermaCare®
that provides warmth. These cells contain a mixture of ingredients (activated
carbon, iron powder, sodium chloride, sodium thiosulfate, sodium polyacrylate
and water) that react with air to provide low-level heat. The chemical reaction
is called iron oxidation, which occurs naturally in the environment." (http://www.thermacare.com/Faq.aspx).
When oxygen is consumed in a closed syringe, the volume must be reduced.
|
ThermaCare®HeatWraps
for neck
|
single heat cell (WK) |
Set-up for
the experiment
|
The
percent of oxygen in air (A
variation of Gregor´s experiment)
Introduction
In the following experiment the chemical reaction between the air and the
ingredients of the heat cells will be measured inside two 50 ml syringes connected
by a Luer
connector for syringes (VB).
In order to compare air with oxygen and with nitrogen the experiment will
be repeated by replacing the air by the other gases.
Material
Photo
3: Tray, scissors, 2 disposable syringes 50 ml, 1
Luer connector for syringes (VB) = B|Braun Adapter w/w, 1 syringe 20
ml, matches, 1 ThermaCare® (neck, wrist & shoulder), air, nitrogen,
oxygen.
Experiment
1. Cut the 10 heat cells from
one of the heatwraps. (Close 9 of them in a film canister).
2. Fill one of the syringes with 50 ml of air, the second one with
a fresh ThermaCare® heat cell.
9. Fill
the emptied 50-ml syringe with 50 ml of oxygen.
3.
Press as much air as possible out of the 2. syringe, write down its volume.
4. Connect the two syringes firmly bound by the B|Braun
Adapter w/w..
5. Press the air into the syringe with the heat cell.
6. Pump the air back and forth between the two syringes.
7. Go on pumping until no more volume change can be observed.
8. Completely fill a 20-ml syringe
with the remaining air. Remove its piston, hold a burning match into it.
10. Repeat 3. - 7.
Write down your observations,
try to explain
them.