Measuring the Effectiveness of
Various Antacids
GABRIELLE CARLINI
Purpose
 To discover which brand of antacid is the most
effective in treating GERD
 To study the effects of adding hydrochloric acid to
different brands of antacids in order to determine
which would resist the pH change
Background Information
 Antacids are agents that neutralize stomach acid.
 Each type of antacid works differently depending on its
main ingredients.
 Hydrochloric acid is the key component of stomach acid. It
has a pH of about 2.
 Gastroesophageal reflux disease, most commonly referred
to as GERD, is a common and usually short-term stomach
condition.
 Antacids are the most common medication, because they
can weaken the acid until the esophagus closes on its own.
Hypothesis
 Because calcium carbonate (Tums), has the highest
pH of the antacids being tested, it will neutralize the
most acid.
Materials
 Burette (1)
 ring stand (1)
 Milk of Mylanta
(750mg)
 Alka-Seltzer
(750mg)
 Tums (750mg)
 Maalox (750mg)
 pH probe and the
corresponding
software
 Computer
 HCL (240mL)
 water
 mortar and pestle
 Funnel (1)
 gloves
Procedure
 1. Dissolve 250mg of Alka-Seltzer into 12mL of water and
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pour into a beaker. Put the beaker underneath the ring
stand.
2. Pour 20mL of hydrochloric acid into the burette and
attach it to the ring stand.
3. Set up the pH probe and place it into the solution. It
should read around 9.
4. Slowly add the acid to the base, one mL at a time.
5. Record the pH after each mL, until the acid has all
been titrated.
6. Repeat 2 more times, then do the same for each other
antacid.
Variables
 Independent- type of base used
 Dependent- pH of the solution
 Control- because this experiment was a comparison,
there was no control group
Data (I)
Magnesium Hydroxide
Aluminum Magnesium
Hydroxide
10
10
8
8
pH
6
4
pH
pH
12
2
pH
6
4
2
0
0
1
3
5
7
9 11 13
mL of HCL
15
17
19
21
1
5
7
9 11 13 15
mL of HCL
17 19 21
Calcium Carbonate
7.6
7.4
7.2
7
6.8
6.6
6.4
6.2
6
5.8
12
10
8
pH
pH
pH
Sodium Bicarbonate
3
pH
6
4
2
0
1
3
5
7
9 11 13
mL of HCL
15
17
19
21
1
3
5
7
9 11 13 15
mL of HCL
17 19 21
Data (II)
Avg. Change in pH
9
8
7
6
5
Avg. Change in pH
4
3
2
1
0
Calcium Carbonate
Sodium Bicarbonate
Magnesium Hydroxide
Alum-Mag Hydroxide
Data (III)
T-Tests
Sodium
Bicarbonate
Magnesium
Hydroxide
Calcium
Carbonate
AluminumMagnesium
Hydroxide
7.15982E-08
0.000319273
8.02605E-05
Calcium Carbonate 0.002738448
0.266112199
x
Magnesium
Hydroxide
x
x
0.963901302
Conclusion (I)
 It was revealed that not all bases resist pH change the same way.
 The aluminum-magnesium hydroxide and magnesium hydroxide
kept the starting pH relatively high because they were very strongly
basic.
 The sodium bicarbonate and calcium carbonate didn’t start with
very high pH’s, but resisted the acid to the point that even after
20mL were added, the solutions were barely acidic.
 The original hypothesis was partly proved, but it was also learned
that the level of the pH is not the only factor determining the
antacids’ effectiveness.
 Antacids that use ingredients such as sodium bicarbonate and
calcium carbonate are much more effective at treating GERD,
because they are able to keep the pH level in the stomach higher for
longer, resulting in a less painful condition.
Conclusion (II)
 Sources of Error
 Some of the antacids were solid and had to be dissolved with
water; which may have affected the overall pH.
 Some of the antacids contained ingredients other than the
main active ingredient which may have interacted with pH
level.
Works Cited
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Antacids. (2011). Retrieved from drugs.com website: http://www.drugs.com/drug-class/antacids.html
a good basic definition of an antacid
Antacids and Acid Reducers. (2010, December 15). Retrieved from WebMD website: http://www.webmd.com/a-to-z-guides/nonprescriptionmedications-and-products-antacids-and-acid-reducers
describes types of antacids and how each one works
Bishop, M. (2010). Titration. Retrieved from http://preparatorychemistry.com/Bishop_Titration.htm
a great procedure for a basic titration (provides many details)
Clark, J. (2002). pH/Titration Curves. Retrieved from ChemGuide website:
http://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html
a good guide for pH and titrations, helps clear up some of the harder language and key terms
Gastroesophageal reflux disease. (2011). Retrieved from US National Library of Medicine website:
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001311/
complete description of GERD, explains why antacids are needed
Gbemudu, A., PhD. (2011). Information on Antacids. Retrieved from Rx List Inc. website:
http://www.rxlist.com/script/main/art.asp?articlekey=95545
complete description of everything needed to know about antacids
GERD, Heartburn, and Acid Reflux. (2009). Retrieved from Relfux Denfense System website:
http://refluxdefense.com/heartburn_GERD_articles/introduction-causes-and-symptoms.html
over view of GERD and recent research on why antacids may not be the best medication
Hazardous Materials. (2008, December 30). In ES&H Manual (pp. Chapter 40) [Pamphlet]. Retrieved from http://wwwgroup.slac.stanford.edu/esh/eshmanual/references/hazmatGuideHydrochloricAcid.pdf
complete description of how to obtain, handle and dispose of hydrochloric acid
Purchon, N. D. (2006, November 10). pH. Retrieved from http://www.purchon.com/chemistry/ph.htm
a basic overview of what pH is
Stomach Acid. (2008). Retrieved from Digestionquestions.com website: http://digestionquestions.com/gerd/stomach-acid.html
complete description of the chemical composition of stomach acid
Tullmin, M. (2002). History of pH. Retrieved from M. Tullmin website: http://www.corrosion-club.com/historypHscale.htm
history of pH
What is pH? (2007, June 8). Retrieved from Environmental Protection Agency website: http://epa.gov/acidrain/measure/ph.html
another overview of pH