Paul Grandstand
Analyzing Antacids
Introduction:
The purpose of this project was to mix and then identify the likely ingredients of
an antacid and put that into a flowchart to help identify substances in three commercial
antacids: Tums, Rolaids, and Alka-Seltzer.
Background:
Antacids are drugs that neutralize the excess acid in the stomach. They contain
the active ingredients, flavoring agents, substances to soothe the walls of the stomach,
and binders, such as cornstarch, to hold the tablet together in the stomach (1). They
prevent what is called hyperacidity or too much stomach acid or HCl (2). Some of the
dangers with excessive use of antacids include kidney stones, a disrupted acid-base
balance in the blood, and Alzheimer’s disease (3). The most common active ingredients
in antacids are magnesium hydroxide, Mg(OH)2, sodium bicarbonate, NaHCO3, calcium
carbonate, CaCO3, and aluminum hydroxide, Al(OH)3 (4). The Mg(OH)2 and the
Al(OH)3 react with stomach acid in an acid base reaction:
Mg(OH)2(s) + 2HCl(aq) → MgCl2(aq) + 2H2O(l)
2Al(OH)3(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2O(l).
The NaHCO3 or CaCO3 react by forming a salt, water, and a gas:
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
NaHCO3(s) + 2HCl(aq) → NaHCl2(aq) + H2O(l) + CO2(g) (4).
The most challenging substance that we had to make in order to analyze an
antacid was anthocyanin. Anthocyanin is made by extracting it from red cabbage and
then adding isopropanol. When a few drops of anthocyanin are added 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). One
interesting note is that although the sodium borate should turn blue-green, it doesn’t
because the borax reacts with the ortho hydroxy groups on the aromatic ring of
anthocyanin, forming a borate salt. As a result, it turns it grey (5).
A substance that we had to make was a copper reduction tablet only in a powder
mixture. This powder was made up of by mass: 1 part copper(II) sulfate, 12 parts sodium
hydroxide, 4 parts sodium carbonate, and 15 parts sodium chloride. When this powder
was added to the antacid, it identified fructose or glucose by giving a reddish precipitate:
C6H12O6(aq) + Cu2+ + NaOH → NaC6H11O7 + Cu2O (red) (5).
These are the half reactions:
e- + Cu2+ → Cu1+ red.
H2O + C6H12O6 → C6H11O7- + 3H+ + 2e- ox.
Another substance that we used was iodine tincture. This reacted with starch,
forming a dark blue starch-iodine complex. This happens when the iodine molecules fit
within the spiral structure of the amylose molecules:
starch + I2 → (blue) (5).
We also had to use lye or 2% NaOH(aq) to detect magnesium sulfate:
MgSO4(aq) + 2NaOH(aq) → Mg(OH)2(s) + Na2SO4(aq).
It detected the magnesium sulfate because only the magnesium sulfate formed an
insoluble hydroxide (5).
Using a flowchart or a qual scheme, we mapped out how we identified what was
in our antacid. Using this, we were able to identify the chemicals in a commercial
antacid.
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 or NaC6H11O7),
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 would smell 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 flowchart we created
to separate the ingredients in commercial antacids.
Results:
Figure 1. Homemade Antacid
Nacl,
NaHCO 3 ,
CaSO 4 ,
sucrose,
fructose,
glucose,
M gSO 4 ,
H 3 BO 3 ,
M SG,
KHC4 H 4 O 6 ,
Na2 B4 O 7
Insoluble
Soluble
CaSO 4 ,
CaCO 3 ,
KHC4 H 4 O 6
NaCl,
NaHCO 3 ,
sucrose,
M SG,
fructose,
glucose,
NaOH,
M gSO 4 ,
H 3 BO 3 ,
Na2 B4 O 7 ,
Na2 CO 3
Turned brown with
iodine tincture
Turned deep blue
with iodine tincture
CaSO 4 ,
CaCO 3 ,
KHC4 H 4 O 6
Bubbled with
addition of vinegar
NaCl,
sucrose,
glucose,
fructose,
M SG,
M gSO 4
Na2 CO 3
Cornstarch
No reaction with
vinegar
Bubbled with the
addition of vinegar
CaSO 4 ,
KHC4 H 4 O 6 ,
CaCO 3
No reaction with
NaOH
Turned to a white
solid with NaOH
Fructose,
glucose,
M SG,
sucrose,
NaCl
M gSO 4
Did not dissolve Dissolved with 10%
with 10% HCl
HCl
CaSO 4
Turned violet with
anthocyanin
KHC4 H 4 O 6
No reaction with
Cu(II)
Turned a red solid
with Cu(II)
NaCl,
M SG,
sucrose
Fructose,
glucose
White solid formed
with 20% HCl
No reaction with
20% HCl
M SG
NaCl,
sucrose
White solid formed
with hot water
No reaction with hot
water
NaCl
sucrose
When I dissolved the homemade tablet in water and filtered, I got both a residue and a
filtrate. When I added iodine tincture to the residue none turned blue. After this, I added
acetic acid. This made the CaCO3 bubble. I then added 10% HCl. The KHC4H4O6
dissolved in the 10% HCl and the CaSO4 did not. We I added anthocyanin to the filtrate,
it turned violet. When I added vinegar, it bubbled identifying Na2CO3. I then added
NaOH. I observed a white solid which was the MgSO4. I then added Cu (II). This
turned fructose and glucose a red solid. Following this, I added 20% HCl. This turned
MSG a white solid. I then added hot water. This turned the NaCl into a white solid. The
rest of the liquid was sucrose.
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
CaCO 3
Unknown
insoluble
ingredients
Turned the
anthocyanin deep
blue
Unknown
soluble
ingredients
no reaction to 2%
NaOH
Unknown
soluble
ingredients
M gOH
Created a white
solid when 2%
NaOH was added
M gSO 4
Did not dissolve in
10 % HCl
Dissolved in 10%
HCl
No reaction with
Cu (II)
CaSO 4
KHC4 H 4 O6
Unknown
soluble
ingredients
No reaction with
20% HCl
unknown
soluble
ingredients
Less soluble in hot
water
Very Soluble in hot
water
Sucrose
NaCl
When I dissolved the Rolaids in water and filtered, I got both a residue and a filtrate.
When I added iodine tincture to the residue, some turned blue, identifying cornstarch.
After this, I added acetic acid. This made the CaCO3 bubble. I then added 10% HCl.
The KHC4H4O6 dissolved in the 10% HCl and the CaSO4 did not. We I added
anthocyanin to the filtrate and it turned a deep blue confirming the presence of MgOH.
When I added 2% NaOH, there was a white solid which was MgSO4. When I added Cu
(II), there was no reaction. When I added 20% HCl, there was no reaction. The sucrose
was very soluble in the hot water, whereas the NaCl was less soluble.
Figure 3. Alka-Seltzer Flowchart
AlkaSeltzer
Soluble
Insoluble
Alka-Seltzer
filtrate,
Unknown
soluble
ingredients
Turned a bluish
green with
anthocyanin
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
Alka-Seltzer had very little in it that I could identify. Through all of my tests, the only
thing that I could identify was that the anthocyanin turned a bluish green, implying that
there was NaHCO3.
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
CaCO 3
Cornstarch
Turned Violet with
anthocyanin
unknown
soluble
Tums
ingredients
NaCl,
sucrose,
fructose or
glucose,
M SG,
M gSO 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 O 6
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
When I dissolved the Tums tablet in water and filtered, I got both a residue and a filtrate.
When I added iodine tincture to the residue, some turned blue, identifying cornstarch.
After this, I added acetic acid. This made the CaCO3 bubble. I then added 10% HCl.
The KHC4H4O6 dissolved in the 10% HCl and the CaSO4 did not. When I added
anthocyanin to the filtrate, it turned violet. When I added 2% NaOH, there was no
Less soluble in hot
water
NaCl
reaction. When I added Cu (II), a red solid formed, identifying fructose or glucose.
When I added 20% HCl, there was no reaction. The sucrose was very soluble in the hot
water, whereas the NaCl was less soluble.
Discussion:
The purpose of this project was to mix and then identify the likely ingredients of
an antacid and put that into a flowchart to help identify substances in three commercial
antacids: Tums, Rolaids, and Alka-Seltzer. As shown in Figure 1, we made a flowchart
of our homemade antacid and used this to identify substances in three commercial
antacids. Using this qual scheme, we found that Rolaids have cornstarch, CaCO3, CaSO4,
KHC4H4O6, Mg(OH)2, MgSO4, NaCl, and sucrose (refer to Figure 2). We found that
Tums contains cornstarch, CaCO3, CaSO4, KHC4H4O6, fructose or glucose, sucrose, and
NaCl. We found that Alka-Seltzer has NaHCO3 because it turned bluish green with the
addition of anthocyanin.
Some suggestions for future work would be: find an alternative method to replace
anthocyanin because it only identifies one group of substances, find out how to identify
other substances in antacids that are listed on the labels of commercial antacids, and see
which antacid can neutralize the most acid. Another idea would be to test more antacids
and do more trials to make it more accurate.
Annotated Bibliography:
1. J. Hill, D. Kolb, Chemistry for Changing Times (Prentice-Hall, Upper Sadler
River, NJ, ed.9, 2001), pp. 196-197.
This textbook had a list of active ingredients matched to the commercial
antacids that use them. J. Hill is from the University of Wisconsin, and D.
Kolb is from Bradley University. This source also talks about the dangers
of excessive use of an antacid for each individual active ingredient.
2. S. Solomon, B. Brook, J. Ciraolo, S. Daly, and L. Jackson, Chemical Education
78, 1475 (2001).
This source from a journal is by far the best source that I have. It has a
flowchart on how to separate all of the chemicals in an antacid and tells, in
more detail, how to make sure that everything works. It also gives
detailed instructions on how to make anthocyanin. One weakness of the
article is that sometimes it is a little vague when describing how to do
something.
3. R. Burns, Fundamentals of Chemistry (Prentice-Hall, Upper Sadler River, NJ,
ed.3, 1999), p. 479.
This chemistry textbook has chemical formulas and talks about the
dangers of having too many antacids. It is written by Ralph Burns of St.
Louis Community College-Meramec. This source is very similar to the
Chemistry for Changing Times textbook.
4. R. Myers, K. Oldham, S. Tocci, Holt Chemistry: Visualizing Matter (Holt,
Rinehart and Winston, Austin, ed. Technology, 2000), p. 568.
This textbook has the most information on the dangers of antacids of all
the sources I have. It is written by R, Myers who is the professor emeritus
of chemistry at Kent State University, K. Oldham who is the professor of
chemistry from Trent University, and S. Tocci who is a science writer in
East Hampton, NY. This is very similar to the Fundamentals of Chemistry
textbook and the Chemistry for Changing textbook, but this book puts
more emphasis on the dangers.
5. M. Armold, Essentials of General, Organic, & Biological Chemistry (Harcourt,
Orlando, 2001), p. 205.
This textbook talks about why the ingredients in an antacid are what they
are instead of other ingredients. M. Arnold is from Adams State College
where he is well known for his general chemistry courses. He received his
PhD in biochemistry from Purdue University. This source also gives
chemical equations of the popular reactions of an antacid tablet. This is a
very different source from all of the other textbooks that I have looked at.