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Antacids: Neutralizing Acid Within the Stomach

Introduction:

Knowing the acidity of a substance or environment can be very crucial to maintaining the safety of everything in the surrounding area. Humans have a strong acid within the stomach known as hydrochloric acid (HCl). HCl is essential as the body uses it to digest the food that comes in. Through this process is how humans can break down all the food eaten to take in the nutrients necessary for survival. The pH balance within the stomach can be disrupted depending on which foods the person chooses to consume. People can also have genetic predispositions to easily upsetting the pH balance within their stomach (Madell, 2012). At an average of a pH 3, the stomach may fall below that level and cause uncomfortable symptoms for which pharmaceutical companies created the antacid. The purpose of antacids is to neutralize stomach acids. An example of such an antacid would be the brands Tums or Alka-Seltzer. There are many other brands that provide acid indigestion relief to customers but there is always one that has a better record at relieving symptoms quicker and stronger. To determine which of four brands neutralizes the drop in pH in the stomach best, a titration technique was used. Phenolphthalein was used as an indicator because of its correlation of color change with pH level. In basic conditions, it is pink and as soon as it becomes acidic it turns clear. The goal was to find the lightest shade of pink which indicates it is right past the neutral point. Using this data, we can find which antacid could provide the best neutralizing effect. Finding out which antacid works better allows for the consumer to know where to allocate their money and invest wisely in a certain brand. It also creates a sense of competition when the other pharmaceutical companies realize they are losing profits to the better drug. Therefore, the effectiveness of the other brands will be tested with and improved.

Experimental Methods:
Materials needed were * 1 volumetric pipette * 1 burette * 1 small jar of phenolphthalein * 1 hot plate * 5 volumetric flasks Multiple trials were conducted until three out of the five trails came within 0.1 mL of each other. A volumetric pipette was used to measure 100 mL of HCl and was put into a beaker. The antacid (in this experiment alka-seltzer) was crushed and poured into the 100 mL of HCl. The beaker was then placed onto the hot plate to remove CO2 which would have acted as a buffer, skewing the results. After the solution in the beaker was heated until bubbles disappeared, it was allowed to cool down for a few minutes. While waiting for the solution to cool, the burette was filled with 50 mL of NaOH (base). The 100 mL of HCl was separated into five different volumetric flasks utilizing a pipette and placing 20 mL in each. Three drops of phenolphthalein were put into each flask containing the 20 mL of the HCl/antacid solution. Using proper titration technique, the NaOH in the burette was poured into the volumetric flasks. Whenever pink was seen, the flasks were stirred. As soon as the pink indicator did not disappear, the titration was stopped. The amount of base was recorded and trials repeated 4 more times.

Results:
Alka-seltzer
| Trial 1 | Trial 2 | Trial 3 | Trial 4 | Trial 5 | HCl (mL) | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | NaOH (mL) | 11.5 | 11.4 | 10.8 | 11.0 | 11.5 |

Antacids by Brand: Class Results | Gelusil | Alka-Seltzer | Alcalak | Medi-First | Amount of Neut.Antacid (mol) | 4.41x10-3 | 6.57x10-3 | 1.375x10-2 | 7.18x10-3 | | 5.81x10-3 | 5.3x10-3 | | 7.25x10-3 |

Average:
11.24 mL NaOH 0.15M * 0.01124 = .001686 moles NaOH

20.0 mL HCl 0.15M * 0.020 = 0.003 moles HCl

.001686 moles NaOH - .003 moles HCl = .001314 moles neutralized by antacid

.001314 moles * 5 = 6.57x10-3 mol per 100 mL

The five trials of NaOH were averaged to get 11.24 mL and multiplied by the molarity of the HCl (0.15M) to reveal the average amount of moles of NaOH within a solution was .001686 moles NaOH. The dependent variable, 20 mL HCl, was multiplied by the molarity of the HCl to determine that there were .003 moles HCl in an average solution. The amount of moles of HCl was subtracted from the moles of NaOH to determine that on average, 0.001314 moles were neutralized by the antacid. With that information, 0.001314 moles was multiplied by 5 to determined that 6.57x10-3 mol per 100 mL would be neutralized.

Conclusion: Because of the time restriction, other lab technicians were assigned the 3 other antacids. The other antacids were Gelusil, Medi-first, and Alcalak (along with Alka-seltzer). For the best results, a piece of white computer paper was held behind the volumetric flask to be able to attain the lightest shade of pink. The trials were done with a starting amount of 20 mL HCl each, which was able to show the results required on a smaller, manageable scale. The results of the average moles neutralized was then multiplied by 5 to attain the amount of moles neutralized per 100 mL. The collected data shows that Alcalak came in as the brand that neutralized the most acid at 1.375x10-2 moles. The following in descending order of amount neutralized are Medi-first, Alka-seltzer, and lastly Gelusil came in as the least effective; one out of the two groups investigating Gelusil at a small amount of 4.41x10-3 moles of HCL neutralized. The results showed that because HCl is such a strong acid, a strong antacid with a high reactivity to the acidic solution is necessary. Calcium carbonate is the only active ingredient in both Medi-first and Alcalak. Calcium carbonate is not only present in both brands, but also in the same amount at 420 milligrams (Medique Alcalak Drug Facts). The inactive ingredients also matchup except for one, corn starch, in Alcalak. This being the only different inactive ingredient shows that corn starch might possibly help Alcalak work better and stronger in the highly acidic environment of the stomach. The results might have been skewed by human error like the accuracy of the amount of base added during the titration process. The results allow consumers to make a cost-effective choice and companies to improve their products.

Works Cited
Madell, R. (2012, June 30). Is Acid Reflux Genetic? Retrieved March 06, 2014, from Healthline: http://www.healthline.com/health/gerd/genetics
Medique Alcalak Drug Facts. (n.d.). Retrieved March 07, 2014, from http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=ae037bb3-122d-4a14-92a1-08a17a5f2a1b