Comparing the Effectiveness of Antacids by Acid-Base Titration, Lab Report Example

Introduction

Antacids work because they cancel out the acidity of stomach acid. As a consequence, their efficacy can be determined based on based on their concentration, as a higher concentration of antacid is needed to neutralize a higher concentration of acid. There are many antacids available on the market and it is therefore valuable for consumers to determine which is the most effective before it is purchased. It is therefore valuable to measure the efficacy of an antacid on the basis of their neutralizing abilities. A common ingredient of antacids is CaCO₃, so the changing concentration of this molecule can be used to determine the efficacy of the drug that it is used in. Two types of antacids that utilize this chemical include tums and the tums generic brand. They are expected to have the same efficacy because they use the same relative proportions of the active ingredient, CaCO₃. It is expected that antacids with a higher concentration of CaCO₃ will be more effective with neutralizing the base, however, the efficacy will be equivalent in this experiment because both antacids have a similar concentration of base.

Materials and Methods

Dilutions of NaOH and HCl were made from 3M stock solutions. The standardization for both chemicals were determined. To determine the neutralization capacity of the antacid, the antacid tablets were first weighed on the gram scale. The tablet was then crushed using a mortar and pestle into a fine powder. 0.2 grams of powder was then transferred to a clean 125 mL Erlenmeyer flask. 10 mL of diluted HCl solution was then added to the Erlenmeyer flask containing the acid. Then, 10 mL of distilled water was added to the flask. The solution was then mixed thoroughly.

To begin the titration, the initial volume of NaOH in the buret was recorded. Two drops of phenolphtalein indicator was added to the flask with the antacid. The acid solution was titrated until the indicator turned a pink color. At the end, the final volume of the NaOH was recorded. This process and analysis was repeated using the second antacid. All solutions were disposed of in the waste container. Associated calculations were then performed.

Data and Calculations

Part I Making a Dilution from Stock Solutions

Sodium hydroxide initial concentration = 3M

Part 2 Standardization of NaOH

NaOH volume = 25 mL

Final volume NaOH = 25 mL – 5.62 mL = 19.38 mL

Part 3 Neutralization of the Antacid

Trial 1

 Trial 2

 Part 4 Titration of the Unreacted HCl

Trial 1

 Trial 2

Discussion Questions

1) molarity x volume = molarity x volume

0.0200 M acid x volume = 3 M base x 50.00 mL

Volume of acid = 0.00013 mL

2) Volume of NaOH used in standardization:

19.38 mL -> 0.01938 L

Molar/Volume = Molar/Volume

3 M/0.025 mL = M/0.01938

The volume of the NaOH used in standardization is 2.32 M.

The percent difference between these is as follows:

2.23 M/3M = .77 x 100 = 77%

There is a 77% difference between the two concentrations. This is indicative that the standardized volume of NaOH is different than the initially measured concentration. In reality, the 2.23 M concentration should be used because it is more accurate with regards to the concentration used in the titration reaction.

3) The concentration of the active ingredient in tums is 0.0220 M.

volume x molarity = volume x molarity

0.010 M x 0.075 mL = 0.022 M x volume

Volume = 0.034 mL

0.034 mL of the antacid is needed to neutralize stomach acid.

4) A little less than twice the amount of acid that was needed to neutralize the tums was needed to neutralize the generic brand.

23.87 mL – 13.63 mL = 10.24 mL

13.63 mL – 7.41 mL = 6.22 mL

6.22/10.24 = 0.61 x 100 = 61%

This is a large difference, indicating that the generic brand is much more effective.

5) If the price for generic and name brand products were the same, it would be better to buy the generic brand because it is more effective. Much less product is needed to neutralize the same amount of stomach acid, indicating the concentration of the active ingredient is higher in the generic brand tablets compared to the name brand. Therefore, even if the generic tablets cost the same as the name brand tablets, they will have a higher value.

Works Cited

U.S. Department of Health and Human Services. Treatment Options for GERD or Acid Reflux Disease: A Review of the Research for Adults. 2011. Web. 10 March 2015. <http://effectivehealthcare.ahrq.gov/index.cfm/search-for-guides-reviews-and-reports/?pageaction=displayproduct&productID=756>