Analyzing Antacids
By Ginny Dines
2005
Introduction:
In this project, we created a homemade antacid, and took it apart using a
qualitative scheme to identify all ingredients in the antacid. We then used our qualitative
scheme to examine three commercial antacids, Rolaids, Tums, and Alka-Seltzer.
Background:
Millions of Americans suffer from a condition called heartburn, or acid
indigestion. Heartburn feels like burning in the chest area, causes a great deal of pain, and
is caused by too much acid (HCl) in the stomach. A healthy stomach has a sphincter in
the lower esophagus blocking off acid from entering the stomach. If this band of muscle
breaks or opens abnormally, acid flows into the stomach, causing heartburn (1).
Heartburn also occurs when the stomachs alkaline mucous lining wears away and the
stomach acids begin to digest the proteins that make up the stomach wall; this is known
as “chemical cannibalism,” and can cause a gastric ulcer (2).
Acid indigestion can be treated with commercial, over the counter antacids.
Antacids, such as Tums, Rolaids, Alka Seltzer, and baking soda, come in a variety of
forms and have varying ingredients. However, they all serve a general purpose. The
antacids are made of bases and weak acids, and they neutralize the overly acidic stomach,
bringing the pH to a healthy 2.3. Many antacids, such as Alka Seltzer, contain sodium
bicarbonate, which reacts with hydrochloric acid to produce carbonic acid, a weak acid,
as seen below (2):
NaHCO3 + HCl  NaCl +H2CO3
The carbonic acid then breaks into carbon dioxide and water:
H2CO3 CO2 + H2O
Other antacids, such as Tums, use calcium carbonate (CaCO3) as the active ingredient.
Many people chose Tums because they not only neutralize acid, but they are also a good
source of calcium. The calcium carbonate in Tums reacts with hydrochloric acid and
produces calcium chloride and carbonic acid (2):
CaCO3 + 2 HCl  CaCl2 + H2CO3
The many different antacids available to the American public can be
overwhelming and confusing. It’s important to remember that the antacids work in
generally the same way, and the choice is dependent on each individual. Important things
to remember are the price, the active ingredient and its side effects, and the ANC, or acid
neutralizing capacity (3).
In our project, we used a qualitative scheme in order to analyze a controlled
antacid as well as three commercial antacids. The qualitative scheme included several
chemical reactions that identified ingredients in our antacids (4).
Iodine tincture was added to the insoluble ingredients in each antacid in order to
see the presence of cornstarch. The cornstarch is identified because one of its
components, amylose, reacts with the I2 and turns it blue (4).
Starch + I2  Blue
We used several solubility tests in our project, starting with solubility in water.
We filtered each dissolved antacid in order to separate out the water soluble form the
water insoluble. We also used 10% HCl and 20% HCl to test solubility. Potassium
Biartrate (KHC4H4O6), which does not dissolve well in water, dissolves with 10% HCl
and produces a highly soluble tartaric acid. 20 % HCl helped us identify the presence of
monosodium glumate (MSG), which reacts with the HCl and produces a white solid,
called glumatic acid, C5H9NO4 (4).
MSG + HCl  C5H9NO4
We used acetic acid to test for calcium carbonate (CaCO3) and sodium carbonate
(Na2CO3). Acetic acid (CH3CH2OH) reacts with these carbonates and produces carbon
dioxide in the form of bubbles (4).
CH3CH2OH + CaCO3 (or Na2CO3)  CO2
In order to find the presence of fructose or glucose, we used a copper oxidation
reduction reaction, using Cu2+ as the oxidizing agent. After creating a copper reduction
tablet, we added it to our antacids and saw that there was glucose or fructose in our
mixture because of a red solid that formed. The red solid came from the reaction between
the glucose and the copper reduction tablet as seen below (4):
Half Reactions:
Reduction Reaction with Cu2+ as the oxidation agent:
Cu2+ + e-  Cu+1 (red solid)
Oxidation Reaction with C6H12O6 as the reduction agent:
H2O + C6H12O6  C6H11O- 7 + 3H+ + 2eWe used anthocyanin as a pH indicator in our project. Because anthocyanin is
difficult to purchase, we extracted it from red cabbage by boiling it in rubbing alcohol.
The anthocyanin helped us identify substances in our antacid by indicating their pH based
on the color that the anthocyanin turned the antacid. Anthocyanin, which is often used as
a pH indicator, turns substances with a pH of 1-3, red; substances with a pH of 4, pink;
with a pH of 5-6, violet; with a pH of 7, violet; with a pH of 8, blue; with a pH of 9-11,
blue green; and with a pH 12 or more green(4).
Procedure:
We began our project by mixing the following ingredients: sucrose, boric acid
(H3BO3), calcium carbonate (CaCO3), calcium sulfate (CaSO4), cornstarch, fructose,
glucose, magnesium sulfate (MgSO4), monosodium glutamate (MSG), potassium
bitartrate (KHC4H4O6), sodium borate (Na2B4O7), sodium carbonate (Na2CO3), sodium
bicarbonate (NaHCO3), sodium chloride (NaCl), and sodium hydroxide (NaOH). We
mixed these ingredients because they are the likely ingredients in commercial antacids.
After creating this mixture, we separated it using a qual scheme. First, using
solubility, we dissolved the mixture in 100 °C water. We then stirred the mixture to help
the dissolving process. We filtered the solution to separate the insoluble ingredients from
the soluble ingredients. Once the residue and the filtrate were separated, we cooled the
filtrate in order to separate the substances that were insoluble at lower temperatures.
Then we filtered the solute again.
For our next step, we needed anthocyanin. To make this we took 500 grams of
red cabbage and processed it in a food processor. We then added 1 liter of isopropanol
and boiled it until there was 50 mL of liquid left in the beaker and filtered it. We did this
under the fume hood because boiling an alcohol gets extremely stinky.
We added the anthocyanin that we made to the solute in order to identify the
water-soluble substances. When we added anthocyanin to the mixture, it turned the
sodium bicarbonate a bluish green (pH 8), sodium carbonate green (pH 11.5), sodium
hydroxide yellow-green (pH 12-13), and boric acid pink (pH 4.5).
Next, we added 5% acetic acid (vinegar) to the solute to see if CaCO3 was
present. We could tell that CaCO3 was present because it bubbled when reacting with
acetic acid. We checked the solute for magnesium sulfate by adding 2% sodium
hydroxide to the solute and observed the reaction.
We added Cu2+ which is an oxidizing agent to the mixture. To make this, we took
by mass, 1 part copper(II) sulfate, 12 parts sodium hydroxide, 4 parts sodium carbonate,
and 15 parts sodium chloride. This created a powder mixture that we used.
After, we added 20% HCl to the antacid. We then added iodine in the form of
tincture. Then we added 10% HCl to turn potassium bitartrate into tartaric acid. We
determined if there was sucrose by putting some of the solution into a spoon and putting
it in a flame. If the sucrose burned, it smelled like sugar.
Once we completed this for our own mixture, we used the scheme to analyze five
antacids. After completely separating our own antacid, we used the quall scheme to
separate the ingredients in commercial antacids. We went through the same procedure in
separating Rolaids, Tums, and Alka Seltzer.
Results:
Our antacid project produced some very interesting results. The ingredients we
were able to correctly identify in our homemade antacid, made from a list of possible
ingredients (4), can be seen in Figure 1 below:
Figure 1: Homemade Antacid Flowchart
Nacl,
NaHCO3,
CaSO4,
sucrose,
fructose,
glucose,
MgSO4,
H3BO3, MSG,
KHC4H4O6,
Na2B4O7
Insoluble
Soluble
Insoluble
Ingredients
Soluble
Ingredients
Turned brown with
iodine tincture
Turned deep blue
with iodine tincture
Turned violet with
anthocyanin
Other
insoluble
ingredients
Cornstarch
NaCl,
sucrose,
glucose,
fructose,
MSG,
MgSO 4
No reaction with
vinegar
other
insoluble
ingredients,
Did not dissolve
with 10% HCl
Dissolved with 10%
HCl
CaSO 4
KHC4H4O6
Bubbled with the
addition of vinegar
CaCO3
Turned bluish green
with anthocyanin
MgOH
No reaction with
NaOH
Bubbled with acetic
acid
Other
soluble
ingredients
Na2CO3
Created a white
solid with 2%
NaOH
No reaction to 2%
NaOH
MgSO4
Other
soluble
ingredients
Turned a red solid
with Cu(II)
No reaction with
Cu(II)
Fructose,
glucose
other
soluble
ingredients
no reaction to 20%
HCl
Created white solid
with 20%HCl
Other
soluble
ingredients
MSG
less soluble in hot
water
very soluble in hot
water
NaCl
sucrose
After separating the soluble ingredients form the insoluble ingredients using
filtration, we were able to use acetic acid to identify CaCO3 in the residue, and we used
10% HCl to find the CaSO4 and the KHC4H4O6 in the residue. In the filtrate, anthocyanin
indicated the presence of NaCl, sucrose, glucose, fructose, MSG, and MgSO4. The
anthocyanin also turned Mg(OH)2 a bluish green. After testing the filtrate with acetic acid
we found the presence if Na2CO3. We identified the presence of MgSO4 with 2% NaOH,
and found fructose or glucose with Cu II.
In our Rolaids tablets we found, cornstarch, CaCO3, CaSO4, KHC4H4O6,
Mg(OH)2, MgSO4, sucrose, and NaCl, as seen below in Figure 2. These ingredients were
identified using the same procedure as used to analyze our homemade antacid (Figure 1).
Figure 2: Rolaids Flowchart
Unknown
Rolaids
ingredients
Insoluble
Soluble
Residue,
unknown
insoluble
ingredients
Filtrate,
unknown
soluble
ingredients
Turned Brown with
iodine tincture
Turned deep blue
with iodine tincture
Unknown,
insoluble
ingredients
Cornstarch
Bubbled when
reacted with acetic
acid
No reaction to acetic
acid
CaCO3
Unknown
insoluble
ingredients
Turned the
anthocyanin deep
blue
Unknown
soluble
ingredients
no reaction to 2%
NaOH
Unknown
soluble
ingredients
MgOH
Created a white
solid when 2%
NaOH was added
MgSO 4
Did not dissolve in
10 % HCl
Dissolved in 10%
HCl
No reaction with
Cu (II)
CaSO 4
KHC4 H4 O6
Unknown
soluble
ingredients
No reaction with
20% HCl
unknown
soluble
ingredients
Less soluble in hot
water
Very Soluble in hot
water
Sucrose
NaCl
As you can see in Figure 3, below, the Alka-Seltzer tablets do not have many
ingredients. There were no insoluble ingredients; no residue was filtered out. We were
able to find only NaHCO3 in the tablets.
Figure 3: Alka-Seltzer Flowchart
AlkaSeltzer
Soluble
Insoluble
Alka-Seltzer
filtrate,
Unknown
soluble
ingredients
Turned a bluish
green with
anthocy anin
NaHCO 3
There was
no residue
Unknown
soluble
ingredients
No reaction with
NaOH
No M gSO 4
No reaction with
Cu(II)
No fructose
or glucose
No reaction with
20% HCl
No M SG
No reaction with
hot water
No NaCl
We found Tums Tablets to have several important ingredients. The insoluble
ingredients were cornstarch, CaCO3, CaSO4, and KHC4H4O6. We found the soluble
ingredients to be NaCl, sucrose, glucose, fructose, MSG, MgSO4, sucrose and NaCl. The
results of the Tums tablets can be seen below in Figure 4.
Figure 4: Tums Flowchart
Unknown
Tums
Ingredients
Insoluble
Ingredients
Soluble Ingredients
Tums
Residue,
Unknown
insoluble
ingredients
Tums
Filtrate,
unknown
soluble
ingredients
Turned brown with
iodine tincture
Turned blue with
iodine tincture
unknown
insoluble
Tums
ingredients
Bubbles formed
when reacted with
acetic acid
CaCO3
Cornstarch
Turned Violet with
anthocyanin
unknown
soluble
Tums
ingredients
NaCl,
sucrose,
fructose or
glucose,
MSG,
MgSO 4
No reaction to 2%
NaOH
No reaction with
acetic acid
unknown
insoluble
ingredients
unknown
soluble
Tums
ingredients
Dissolved in 10%
HCl
Did not dissolve in
10% HCl
KHC4 H4 O6
CaSO 4
No reaction to
Cu (II)
Formed red solid
when reacted with
Cu (II)
unknown
soluble
Tums
ingredients
fructose or
glucose
No reaction to 20%
HCl
unknown
soluble
Tums
ingredients
Very soluble in hot
water
Sucrose
Less soluble in hot
water
NaCl
Discussion:
In our project, we successfully created our own antacid and used it to find the
ingredients in Tums, Rolaids, and Alka-Seltzer. These antacids contained many like
ingredients, and some unique ingredients.
We were successful in making and separating our own homemade antacid. We
found that all the ingredients we put in came out through our qualitative scheme (Figure
1). Using our flow chart from the separation of our homemade antacid, we began to look
at commercial antacids.
We found that the Rolaids tablets had many of the likely ingredients used in our
homemade antacid. There was a presence of cornstarch, which is used as a binder to keep
the tablet together. We also found calcium carbonate, CaCO3 (one of two active
ingredients present), CaSO4, and KHC4H4O6. The other active ingredient was found to
be, magnesium hydroxide, Mg(OH)2, MgSO4, NaCl, and sucrose were also found.
Tums tablets contained many of the same ingredients as Rolaids, such as
cornstarch, CaCO3, CaSO4, KHC4H4O6, Sucrose, MgSO4 and NaCl. The Tums also
contained fructose or glucose, and MSG. However, the Tums did not contain Rolaids’s
second active ingredient, Mg(OH)2. The two antacids are similar, but not the same. AlkaSeltzer is very different from both of these antacids. In the Alka-Seltzer tablet, we found
only one ingredient, sodium bicarbonate (NaHCO3). This means that Alka-Seltzer is by
far the simplest antacid of those tested.
If antacids were to be further studied, I would recommend studying more antacids
in hopes of finding a wider comparison. I would also allow more time for more trials to
be done to increase the accuracy of our tests.
Sources:
1. Mayo Clinic, “Heartburn/GERD,” (2004) http://www.mayoclinic.com Accessed 2005
February 13.
The Mayo Clinic, one of the most recognized hospitals in the country, offers this
article on their website. This article describes heartburn, which is the condition
that antacid treats. The article discusses the causes of Heartburn, and possible
treatments including commercial antacids. There are many reasons for heartburn,
such as bad eating habits, certain medications, and alcohol consumption. No
matter what the cause, heartburn is a condition that needs to be treated. Knowing
about the condition helps us to see what antacids need to do in our projects.
2. C. Snyder, The Extraordinary Chemistry of Ordinary Things (John Wiley and Sons
Inc, New York, 1992), pg. 282-284.
The Extraordinary Chemistry of Ordinary Things is a book about the chemistry
behind day-to-day life. Antacids are featured in this book because they’re
seemingly simple over the counter drugs that have a lot of chemistry behind them.
The pages I used talk about the need for antacids, and how they work. There is a
lot of information on gastric ulcers and heartburn. There is also a lot of
information on the active ingredient s in several commercial antacids, and the
reaction they go through in order to neutralize
and overly acidic stomach.
3. G. Martin, Journal of Chemical Education 65, 214-216 (1988).
“Rating Antacids in Consumer Reports,” by Geoffrey Martin of Consumers
Union, explores and compares the many different commercial antacids. This is
important to our project as we decide which antacids to use in our project. This
article looks at the Acid Neutralizing Capacity (ANC) of several antacids and
compares their pHs in a titration simulation. G. Martin used this experiment to
rate Maalox, Tums, Rolaids, and other antacids based on there dosage, ANC,
price, and effectiveness. This was a very useful source because of its interesting
comparison of the different antacids.
4. M. Oliver-Hoyo and D. Allen, Journal of Chemical Education, 78, 1475-1479 (2001).
This article, from the Departments of Chemistry at North Carolina State
University and Drexel University, gives a very detailed overview and explanation
of the procedure we adapted. It provides information on why each step is
necessary in our experiment. It also gives important background information on
antacid tablets, and a very useful flow charts that guides our experiment.
5. B. Straume and K. Furu, Journal of Clinical Epidemiology, “Use of Antacids in a
General Population,” Vol: 52 (1999) Available from: <http://e5500.fapesp.br/> 2005
February 11.
This article, taken from The Journal of Clinical Epidemiology, describes a study
designed to test the use of antacids by different people. The study was interesting
because it looked at whether antacids are over used by certain populations. The
experiment was done in affiliation with the research center for epidemiology, the
Institute of General Practice and Community Medicine, and The University of
Oslo.
6. J. Hill, D. Kolb, Chemistry For Changing Times (Prentice Hall, New Jersey, Ninth
Edition, 2001).
This source provided useful information on some of the ingredients in antacids.
The article gave the active ingredient in several popular antacid brands. This is
important information for us to know in our project as we analyze different
antacids. There was also information on the condition hyperacidity, which
antacids are used to treat, and it gave some of the problems of the ingredients of
antacids. Overall this source had some very useful background information.