How effective are OTC antacid tablets?

Abstract

When eating or drinking too much, people can face heartburn and certain stomach issues due to the build up of gastric acid found in the stomach. To neutralize the acid in the stomach an individual can take an antacid tablet. There are many different brands that sell antacid medicine. In this lab we will test three different antacid brands to see which one of them is the most effective according to cost and amount of acid neutralized per tablet.

Introduction:

By using titration methods, students can compare the effectiveness, both the cost and the mass, of varying brands of antacid tablets. Titrations is a laboratory technique used to determine the quantity of an unknown reagent (called analyte) by adding a reagent (called titrant) with a known concentration. The titrant chemically reacts with the analyte. To be able to determine the exact amount of acid neutralized by base, we will use an indicator , a substance added to the titration, which changes color at the endpoint (where the solution turn from acidic to basic). The purpose of this lab is to determine the ability of antacids to neutralize hydrochloric acid by looking at different brands and comparing their efficiency. In this lab we will use the data received from titrating a solution and plug those values into a set of equations and compare.

Materials:

• Goggles
• Thermometer
• Pipette
• Antacid tablets
• 250 mL Erlenmeyer flask
• Hot plate
• Scale
• Hydrochloric Acid (HCl) and Sodium hydroxide NaOH
• Burette

Procedure:

• We will use the following masses of Antacid tablets:

Brand name	Mass used	HCl volume
Tums	0.50-0.55g	50 mL
Alka-Seltzer	0.50-0.55 g	50 mL
Alcalak	0.35-0.40 g	50 mL

• Take one of tablet of each of the antacid using gloves, weigh the desired amount  and transfer it to a clean 250 mL flask. Each sample will be tested individually
• Add the required amount of HCl to each of the flasks, and mix until dissolved
• Boil for 2-3 minutes on a hot plate to speed the reaction and remove any excess carbon dioxide.
• Leave solution to cool down to room temperature.
• Prepare a burette for titration with 0.1 M sodium hydroxide (NaOH)
• Add 3 drops of phenolphthalein indicator to the solution in the flask
• Titrate solution slowly  with NaOH until you observe a color change. The end point is a very light shade of pink.
• Record your volume of NaOH used.

Data and analysis:

To narrow down the error margin, each sample antacid was tested 6 times. The experiment gave the following results:

Mass of Tums tablet (g)	Volume of NaOH used (ml)	Mass of Alka-Seltzer tablet (g)	Volume of NaOH used (ml)	Mass of Alcalak tablet (g)	Volume of NaOH used (ml)
0.51	9.3	0.51	39.1	0.36	3.6
0.55	9.4	0.54	38.3	0.37	3.3
0.5	9.8	0.53	47.9	0.37	3
0.5	8.3	0.53	46.1	0.34	7.9
0.55	8.1	0.54	41.5	0.35	2.9
0.54	8.7	0.53	33	0.38	4.2

Mass of Antacid tablets vs the volume of NaOH needed for neutralization (Morsy, 2018.).

We can calculate the average of Trials of each tablet after eliminating trial 6 of Alka-Seltzer and trial 4 of Alcalak, because they’re far from the average.

Tums:

0.525g neutralized by 8.9 ml of NaOH

Alka-Seltzer

0.53g is neutralized by 42.58 ml of NaOH

Alcalak

0.37g is neutralized by 3.4 ml of NaOH

To calculate Mass and cost effectiveness of all tablets we need to do the following

Sample calculation for Tums

• Moles of HCl=0.05L*0.1M=0.005 moles
• Moles of NaOH required to back titrate excess HCl=0.0089L*0.1M=8.9E-4 moles
• Moles of HCl neutralized per sample=0.005-0.00089=4.11E-3 mole
• Moles neutralized per tablet=4.11E-3*(1.33g/0.525g)= 0.0104 mole
• Mass effectiveness= Moles of HCl neutralized per tablet/ Mass of Antacid = 0.0104mole/1.33g=7.83E-3 mol/g
• Cost effectiveness = Moles of HCl neutralized per tablet/ cost per tablet= 0.0104 moles/5.58cents= 1.864E-3 mol/cent

Alka-Seltzer

• Mass effectiveness= Moles of HCl neutralized per tablet/mass of tablet= 4.675E-3 mole/3.54grams= 1.32E-3 moles/grams
• Cost effectiveness= Moles of HCl neutralized per tablet/ cost per tablet= 4.675E-3

/24.31cents= 1.92E-4 mol/ cent

Alcalak

• Mass effectiveness=Moles of HCl neutralized per tablet/ Mass of tablet= 8.56E-3 mol*0.68=1.856E-3 mol/g
• Cost effectiveness= Moles of HCl neutralized per tablet/ cost per tablet=8.56E-3*4.612cents= 1.856E-3 mol/cent

The best mass effective tablet is Tums at 7.83E-3 moles of HCl neutralized per gram of tablet used.

The best cost effective tablet was tums at 1.864E-3 moles of HCl neutralized per cent.   

Discussion: This lab helps explain the logistics behind the use of antacid tablets and how effective they are in neutralizing the acid located inside the stomach. By using titration we can eliminate a lot of random error because we are not making judgments on the final volume, rather we are using a device to calculate the total volume used. For the second part of the lab we are performing two different calculations to calculate price and mass effectiveness. The calculation performed shows that Tums is most effective in both categories and this is because it has the highest value for moles of HCl neutralized per tablet. A couple of data point were far from the average and had to be eliminated. The errors may have happened due to a number of reasons such as;  possible contamination of antacids tablets if they were touched by hand or by touching the scale, adding the HCl right after the solution was removed from the hot plate and leaving it to room temperature. Overall most of the data points seem consistent which proves the validity of the experiment.

Conclusion: In this lab we were able to use titration and 2 simple equations to evaluate the effectiveness, both cost and mass, of three different antacid tablets. This experiment focuses on how bases and acids mix, but the main point of this lab is to learn more about titrating solutions. During Base- Acid titration. The amount of base starts to increase in the solution until it reaches the equivalence point (where the amount of acid and base are exactly the same) and that’s when the solutions turns pink. While experimenting we are trying to find out which antacid tablet neutralizes 50 mL of acid most effectively. After collecting all the data we found that the antacid tablet Tums is the most cost effective and the most effect when pertaining to mass. If you were to recommend an antacid tablet to a fellow colleague the best brand would be Tums because it is the best at neutralizing acid at the best cost and mass.

Acknowledgment:

Thanks to Hunter College that allowed me to participate in this experiment especially professor Parminder Kaur along with my colleagues:

• Omar Emara
• Kevin Lorenzo
• Ealan Nisanov
• Timothy Keo
• Justin Wang
• Kathleen Lee

References

Antacids | How do antacids work? (n.d.). Retrieved from https://patient.info/health/indigestion-medication/antacids

Bel Marra Health. (2018, August 02). What causes excessive stomach acid and how to get rid of it. Retrieved from https://www.belmarrahealth.com/causes-excessive-stomach-acid-get-rid/

Britannica, T. E. (2017, October 06). Titration. Retrieved from https://www.britannica.com/science/titration

Morsy, A., (2018, October 01). Mass of Antacid tablets vs the volume of NaOH needed for neutralization.

Silumbe, K., Yukich, J. O., Hamainza, B., Bennett, A., Earle, D., Kamuliwo, M., . . . Miller, J. M. (2015, May 20). Costs and cost-effectiveness of a large-scale mass testing and treatment intervention for malaria in Southern Province, Zambia. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490652/