All
of the experiments must be done in the presence
of a parent or teacher.
Experiment
7: Why Does Alka-Seltzer Make Your Upset
Stomach Feel Better?
Ideas | Materials | Procedure
| Ideas |
|---|
|
The bromphenol blue is an acid/base
indicator. Vinegar is acidic, as is
your stomach. Bromphenol blue turns
yellow in the presence of excess acid,
as is the case when the vinegar is
added to the water. When too much
acid builds up in your stomach, it
can feel upset. Alka-Seltzer is a
"buffer" which keeps your
stomach from being too acidic. This
is demonstrated by the fact that the
Alka-Seltzer turns the solution back
to blue – indicating the acid
has been neutralized.
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| Materials |
|---|
|
Note: All experiments should be
done using original formula effervescent
Alka-Seltzer.
- Alka-Seltzer tablet
- 100ml (1/2 cup) of water
- Vinegar
- Bromphenol blue indicator
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| Procedure |
|---|
|
1. To about 100ml (1/2 cup) of
water add 5-10 drops of bromphenol
blue indicator. Water must turn blue.
2. Add a dropper full of vinegar.
The water will turn yellow.
3. Add an Alka-Seltzer tablet. As
it starts to fizz, the color changes
back to blue.
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