Antacid Lab Report

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Walden University *

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116

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Chemistry

Date

Apr 3, 2024

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pdf

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Uploaded by ElderDangerSeahorse7226

Grace - Discussion Kyle- Results Truan- Procedures How Effective is the Antacid? Procedure- In order to complete the following lab we had to first and foremost follow all lab safety rules and regulation to ensure a safe environment. After confirming safety we had to list our objectives for the following experiment. Our objectives were to Neutralize 1.5M of HCL with NAOH, determine the endpoint, and calculate the molarity of the solution. We also had to perform multiple striations for the following experiment to make sure that our results remained consistent between trials. After the objectives were determined we had to utilize a data table that we created prior to the meeting of the lab to record all information necessary to complete the objectives and any additional questions on the provided lab handout. The procedures for the titration of the anti-acid included the following steps: 1. Add 40-50mL of boiled distilled water to the glassware containing the antacid tablets. 2. Add the assigned dose of the antacid to the glassware. 3. Add the recommended volume of 1.5M HCl to the glassware containing the antacid tablets. Use analytical equipment to precisely measure the volume of HCl added.

4. Stir the solution using a hot plate on a medium setting with a stir bar. 5. Determine the pH of the solution using the most suitable pH detecting technique. Record the pH in your notebook. 6. Neutralize the excess HCl in the Erlenmeyer flask by titrating with standardized NaOH solution. Use analytical equipment to precisely record the volume of NaOH added. 7. Perform multiple trials as necessary. 8. Record observations, sources of error, and safety considerations in your lab notebook. 9. Clean up your bench area and return equipment to the instructor. Collect HCl, KHP, NaOH, and antacids in the waste bottle in the fume hood. Results- Table I- Litmus Paper pH Meter After Adding 2-3 Drops of Universal Indicator Acidic, Basic or Neutral?

Substance What color does the red litmus paper turn? What color does the blue litmus paper turn? What it the pH meter reading? What color does the substan ce turn? What is the pH for this color? Vinegar Red Red 3.29 red /orange 3-4 Acidic Baking Soda + DI water Blue Blue 8.36 Bluish green 8 Basic Tap Water Red Blue 7.12 Light green 7 Neutral pH<7 Acidic pH=7 Neutral pH>7 Basic Table II- Mass of KHP (g) Moles of KHP (mol) Initial and Final Buret Reading Total Volume (mL) Molarity of NaOH (M) Average Molarity of NaOH (M) Trial 1 0.4 g 1.959 x 10 -3 I: 1.70 F: 5.80 4.1 mL 0.4778 M 0.4565 M Trial 2 0.4 g 1.959 x 10 -3 I: 5.80 F: 10.30 4.5 mL 0.4353 M 0.4565 M Calculations- G of Khp x (1 mol of KHP/204.23 g of KHP) x (1 mol of NaOH/ 1 mol of KHP) 0./4g/204.23g= 1.959x10^-3 Repeat this process for 4.5 mL To find the average molarity of NaOH- Molarity of NaOH trial 1 plus trial 2 divided by 2 0.4778+.4353=0.913 0.913/2= 0.4565 M Table III-

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Trial Volume of 1.5 M HCl added (ml) Acid added (mmol) NaOH initial burette reading (ml) NaOH final burette reading (ml) Total Volume of 0.4565 M Na OH added (ml) Base, NaOH added (mmol ) Amount of HCl neutraliz ed by antacid (mmol) Averag e Amount of HCl neutrali zed by antacid (mmol) 1 15mL 1 pink tablet 5.8 mL 25 mL 19.2 mL 8.764 8 mmol .013735 2 -1.52 2 15 mL 1 Orange Tablet 21.25 27.98 6.73 3.07 mmol -3.05 -1.52 Calculations- Total Volume of .4565 NaOH added- Final Burette reading- Initial reading 25-5.8=19.2 mL Amount of HCI neutralized- 1.5(0.015)-6.73(.4565)= -3.05 Average amount of HCI neutralized- Amount of HCI trial 1 +Trial 2 diveded by 2 .0137352-3.05=-3.036 3.036/2= -1.52 Discussion: The purpose of this experiment was to determine how effective various antacid tablets are when neutralizing excess stomach acid. Antacids contain active ingredients that are bases, in order to react with the acid in the stomach. Before beginning the experiment, we tested various methods of measuring pH. Litmus paper, a digital pH meter, and a few drops of Universal Indicator were all used to measure the pH of three different test substances (Table 1). While all three methods effectively determined whether the substances were acids or bases, the pH meter was much more accurate and precise than the other methods. Next, to further prepare for the main experiment, we determined the average molarity of NaOH, by standardizing a sample of sodium hydroxide. The chemical potassium hydrogen phthalate (KHP) was used to make a solution in which we could accurately calculate the molarity of NaOH (Table 2). According to

the lab worksheet, “NaOH is hygroscopic, meaning that water will adsorb to the surface of the solid NaOH that was used to create the reagent solution you have before you. Therefore, a primary standard that is not hygroscopic, like potassium hydrogen phthalate (KHP), is used to make solutions for which accurate molarities can be obtained.” After two trials, it was determined that the average molarity of NaOH was 0.4565 M. Using this data we moved on to the third part of the experiment, testing the antacid tablets. In order to determine the antacid’s effectiveness in the lab, we used a technique called titration, more specifically, back-titration. First, we prepared a solution with 15 mL of HCl, 50 mL of DI water, a pink antacid tablet (KHP), and 2-3 drops of 1% phenolphthalein indicator. This solution was heated and stirred with a stir bar over a hot plate until the antacid tablet was completely dissolved. This solution started as a bright, salmon color, and the goal was for it to turn colorless after a certain amount of NaOH added. A buret was primed, to avoid dilution, and prepared with NaOH, and the initial buret reading was measured. Slowly, the NaOH was dropped from the buret into the beaker containing the HCl solution, until (ideally) the solution turned colorless. After about 25 mL of NaOH was added, however, the solution still did not turn colorless. The solution was more of a light orange color. Nonetheless, the number of moles of HCl that were neutralized were recorded, along with other readings, on Table 3. While the failure to get a colorless solution could have been human error in the experiment, this problem was seen by multiple groups in the lab. Those that used the pink tablet were not able to see their solution turn clear. This could be due to faulty tablets or too much acid, but in general, the process showed the ineffectiveness of the pink antacid tablets.