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Kreidler, Kathy Thornridge High School
Over one-half billion dollars are spent on over-the-counter antacids
every year. An informed consumer will understand how antacids work and
will read the labels to see what ingredients are present. Based on this
information and on a knowledge of side effects, the student consumer
will be able to decide which, if any, antacid to choose.
6 250 ml Erlenmeyer flasks baking soda
6 balloons Tums
600 ml 0.1 M hydrochloric acid Rolaids
Alka Seltzer Phillips Milk of Magnesia
Maalox tablets methyl orange indicator
Before class starts, prepare 6 little stomachs. These are 250 ml
Erlenmeyer flasks, each containing 100 ml of 0.1 M HCl and a few drops
of methyl orange indicator. Put an empty balloon over the mouth of the
control flask. Crush one dose of each antacid and place in a balloon.
Label the bottom of each flask to correspond to the antacid in the
balloon. Place the balloons over the necks of the flasks, but do not
allow the antacids to fall into the flasks yet.
Tell the students that you have an upset stomach from eating too much
pizza last night. Ask what you could take to get relief from
indigestion and "sour stomach." Place samples of antacids on the desk.
Explain the little stomachs setup. Shake the balloons so the antacids
fall into the flasks. Record student observations and explanations on
Pass out a list of ingredients of common antacids. The list could also
include the price per dose. Ask what ingredients could neutralize acid
and what ingredients could relieve gas pains.
Write representative neutralization equations. Explain the action of
simethicone. Tell some of the side effects of aspirin, magnesium,
aluminum, and sodium salts. Discuss the function of the inactive
ingredients. Ask the students to use this new information and their
observations to guess which antacid was in each flask.
Students work in groups to decide which antacid is the best. Each
group shares its decision and the criteria used to arrive at that
Eby, Denise and Roger Tatum. The Chemistry of Over-the-Counter Drugs.
Unigraph: Seattle, Washington, 1977. pp.14-21.
Graedon, Joe. The People's Pharmacy. St. Martin's Press: New York,
Rombauer, Irma S. and Marion Rombauer Becker. The Joy of Cooking.
Bobbs, Merrill: Indianapolis, 1962. p. 557.
Strongin, Herb. Science on a Shoestring. Addison Wesley: Menlo
Park, California, 1985. pp. 41-43.