Chemistry Experiment, effects of antacid PDF

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How effective are different antacids and how can you test for it....

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1 TITLE COMPARING AND MEASURING THE EFFECTIVENESS OF ANTACID TABLETS USING AN ACID TITRATION.

1.0 Introduction When we studied acid-based reactions in class, I was intrigued by the ability of a base to bring the PH of an acidic environment, back to the preferred PH level. Within the world, people suffering from stomach acidity were 595,402 in 1998. In 2005, there were 2.14 million, an increase of 216 percent, which encouraged the creation of antacid tablets to be more efficient in solving the problem of acidity. From a young age, the phrase of “I’m having acidity” was very commonly heard within my family. As a 9-year-old, seeing an adult repeatedly having this issue, and eating a pill that cures it all, was very magical without knowing the Chemistry involved within it. I later learned in my Chemistry class, that the base ingredient within the antacid tablet, neutralizes the PH of the stomach by reacting with the Hydrochloric Acid. I then decided to delve deeper into the active ingredients within the antacids that cause these reactions to happen, and whether they all have a similar effectiveness at neutralizing the acid within the stomach. Through this I came to know that many brands of antacids contain calcium carbonate, which is a white powdery solid that is easily pressed into a tablet, and other compounds. When chewed and swallowed, the calcium carbonate reacts with hydrochloric acid in a typical neutralization reaction: CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l) Given the different active ingredients different brands of antacids contain, I decided to explore the effectiveness of 3 different brands, by formulating the research question: To what extent do varying masses of Calcium carbonate present in each antacid tablet determine the volume of HCl neutralized, by titrating aqueous solution of 5.0 g antacid tablet dissolved in 10 cm³ HCl against standard (0.01 M) NaOH solution at RTP?

1.1Background Information

2 HCl is an acid that catalyzes the formation of pepsin. Pepsin is an enzyme that digests proteins that are found in meats, eggs, and dairy products. The enzyme is present within the stomach, and in order for it to be effective, the pH of the stomach must remain below 3.0. Situations that may cause stress or overindulgence, can interfere with the PH level of the stomach, making it drop to 1.0 or less, causing the environment to be extremely acidic. Therefore, antacids are used to neutralize the PH of the stomach, bringing it back to PH 3. Through previous research, it was discovered that antacids can be made from a variety of compounds, but must contain a base in order to neutralize the excess hydrochloric acid produced by the stomach. Antacids that contain calcium carbonate or aluminum dissolve more slowly and can take up to thirty minutes to begin working. The base most of the times is not a very strong base, as it could cause damage to the mouth and oesophagus on the journey to the stomach. The most common bases used to neutralize the PH level of the stomach are: Compound

Chemical

Neutralization reaction

Aluminum hydroxide Magnesium hydroxide

formula Al(OH)3 Mg(OH)2

Al(OH)3 (s) + 3HCl (aq) → AlCl3 (aq) + 3H2O (l) Mg(OH)2 (s) + 2HCl (aq) → MgCl2 (aq) + 2H2O (l)

Calcium hydroxide Sodium carbonate Sodium bicarbonate

Ca(OH)2 Na2CO3 NaHCO3

Ca(OH)2 (s) + 2HCl (aq) → CaCl2 (aq) + 2H2O (l) Na2CO3 (s) + 2HCl (aq) → 2NaCl (aq) + CO2 (g) + H2O (l) NaHCO3 (s) + HCl (aq) → NaCl (aq) + CO2 (g) + H2O (l)

By measuring the amount of acid neutralized, the initial amount of base can be determined. The stronger the antacid, the more acid it can neutralize. For example, Eno uses the base calcium carbonate (CaCO3) as the active ingredient. For each molecule of calcium carbonate, two molecules of acid are neutralized. CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l) In order to perform this experiment, I had to familiarize myself with the optional topic of Medicinal Chemistry and understand the process of acidity. This experiment allows me to conclude what is the most effective antacid that can be used for individuals with acidity and excess acid reflux issues.

1.2 Hypothesis If I dissolve the tablet with the greatest mass of Calcium Carbonate (Eno) into HCl, and titrate it against NaOH, it will neutralize the highest volume of HCl due to the reactants

3 being present in greater amounts. Acids act as proton donors, therefore release H+ in solution while bases act as proton acceptors therefore take up H+ in solution. Therefore, I believe that Eno will be able to accept or take up the largest number of H+ as it has the most mg (855) of CaCO3.

1.3 Design Independent Variable: Mass of the active ingredient (CaCO3) present within each brand of Antacid. Eno – 855 mg, Gaviscon – 500 mg, Maalox – 200 mg Dependent Variable: Volume of NaOH used within the titration to completely neutralize the solution after each antacid has been added to the HCl, measured through the change in PH using the PH meter. Controlled variables: Variable controlled

Why it’s important to control

How the experiment will control or monitor the variable

Mass of each Antacid used. (5.0 g)

In order to determine the rate at which the antacid reacts, each trial would need to produce similar amount of product with similar amounts of reactants. The amount of acid dissolving the tablet needs to be constant to ensure similar concentrations and amounts present in each particle of the solution. To ensure the concentrations of both reactants are equal.

The same mass of each antacid reacting ensures a similar yield of reactant reacting with the acid.

To avoid any fluctuations in results due to temperature.

To ensure no external influences on rate of reaction.

Concentration of HCl (0.1 M dm³) as the PH of the stomach varies between 1.5 to 3.5 Constant concentration of NaOH (0.1 M dm³) used in the titration

Temperatures of solutions (Room Temperature)

2.0 Procedure & Safety Apparatus

10cm³ of 0.1 M HCl will be used from the total of 500cm³ for each trial.

The mole ratio between NaOH and HCl is 1:1 therefore equal concentration of base will neutralize the acid.

Chemicals/ Reagents: 1) 9 Antacid tablets (3 of each): Gaviscon, Maalox and Eno 2) 250 cm3 of 1 M HCl

4 1. 50.0 cm3 burette ± 0.1 cm3 2. Mortar and Pestle (x 3) 3. Electronic Balance ± 0.01 g 4. 2.0 cm3 pipette ± 0.1 cm3 5. 25.0 cm3 pipette ± 0.03 cm3 6. 10.0 cm3 measuring cylinder ± 0.1 cm3 x6 7. 100.0 cm3 measuring cylinder ± 0.1 cm3 8. Spatula x 4 9. PH meter 10. Stirring plate and magnetic stir bar

2.1 Procedure 1. Crush the recommended dose (use 2 tablets) of every type of antacid using a mortar and pestle. Ensure that the powder is as fine as possible, so that it resembles flour and has a greater surface area. 2. Measure 5.0g of each antacid using the electronic balance and each antacid measured is the same mass. (5g) 3. Transfer each powdered antacid tablet into a 250 ml beaker. 4. Measure 100 mL of 0.1 M HCl using the100 cm3 measuring cylinder. 5. Pour the acid into the beaker that contains each powdered antacid. 6. Place the mixture of the acid and the antacid on to a stirring plate, in order for the solution to react and dissolve completely and no lumps are formed at the bottom of the beaker. 7. Test the pH of the solution using a pH meter and record this value as your initial PH, with the dissolved antacid. 8. Transfer 10 cm³ of this solution to a 100 mL beaker using a measuring cylinder. 9. Fill a burette with 0.1 M NaOH and record the initial volume of the solution. 10. Place the PH meter electrode into the beaker containing 10cm³ of the dissolved solution. 11. Add small volumes of NaOH from the burette into HCl solution, while carefully observing the changes in PH.

5 12. When the pH reaches 10.00 and remains at or slightly above this level for 30 seconds, stop adding the NaOH solution. 13. Record the final volume of the NaOH from the burette on your data sheet. 14. Repeat the process for each antacid, noting and recording the PH of the solutions when necessary. 15. Ensure uncertainties are recorded after each reagent is measured.

2.2 Safety Issues Hazard

Precaution

Safety: Sodium Hydroxide (NaOH) causes severe skin irritation and eye irritation.

Even though the concentration to be used is 0.1M it is advised to wear safety goggles and gloves at all time when using this chemical.

Safety: Hydrochloric acid causes skin irritation and is highly acidic

Wear safety goggles and gloves and keep eyes at distance from solutions.

Safety: Fragile lab wares to be handled with care

It is advised to keep lab wares carefully and away from edges to ensure no harm or breakage occurs.

Environmental: disposal of solution containing sodium hydroxide and HCL (NaOH)

The antacid tablets combined in solution have no particular environmental hazard, however, due the OH- ions present in sodium hydroxide is harmful for aquatic life. However, due to the low concentration of NaOH, 0.1, it can be disposed of in the water drain.

2.3 Setup

Burette filled with 0.1 M NaOH

PH meter recording PH after of NaOH is added

Beaker with 10 mL of dissolved antacid in HCl 250ml

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3.0 Data Tables 3.1 Qualitative Data

Effervescence was observed through the reactions of Maalox and Gaviscon with HCl due to Calcium Carbonate breaking down, resulting in the release of Carbon dioxide 3.2 Quantitative Data Antacid Brand

Mass of CaCO₃ (mg) in tablet

Initial Volume of NaOH/cm³

Final Volume of NaOH/cm³

±0.1cm3

±0.1cm3

Gaviscon

Volume of NaOH used to reach PH 10 (cm³) ±0.1cm3

Trial 1

500

0.00

6.50

6.50

Trial 2

500

0.00

6.90

6.90

Trial 3

500

0.00

6.50

6.50

Average

500

0.00

6.50

6.63

Raw Data of Mass of Calcium Carbonate Vs Volume of NaOH used. Antacid Brand

Mass of CaCO₃ (mg) in tablet

Eno Trial 1

855

Initial Volume of NaOH/cm³

Final Volume of NaOH/cm³

±0.1cm3

±0.1cm3

14.00

18.20

Volume of NaOH used to reach PH 10 (cm³) ±0.1cm3 4.20

7

Trial 2

855

14.00

18.10

4.10

Trial 3

855

14.00

18.00

4.00

Average Antacid Brand

855 Mass of CaCO₃ (mg) in tablet

Maalox

14.00 Initial Volume of NaOH/cm³

17.10 Final Volume of NaOH/cm³

±0.1cm3

±0.1cm3

4.10 Volume of NaOH used to reach PH 10 (cm³) ±0.1cm3

Trial 1

200

4.00

12.40

8.40

Trial 2

200

4.00

12.38

8.38

Trial 3

200

4.00

12.38

8.38

Average

200

4.00

12.39

8.39

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Calculating percentage uncertainty Percentage uncertainty =

Absolute uncertainty x 100 Reading

Percentage uncertainty of mass of tablets = 0.1 x 100 =1.51% Example – Volume Uncertainty = 6.63 0.01 x 100=0.2 % Mass Uncertainty = 5 0.1 x 100 =1% Sample of HCl used = 10 Total Uncertainty = 1.51+0.2+1 = 2.6% = 3.0 Antacid

Gaviscon Eno Maalox

Mean Volume of NaOH Used cm3 6.63 4.10 8.39

Mass of Antacid used (g) 5.00 5.00 5.00

Sample of HCl used in titration cm3 10 10 10

Total Percentage Uncertainty 3.0% 4.0% 2.0%

Average Data Antacid Tablet Gaviscon Eno Maalox

Mass of CaCO₃ (mg) 500 855 200

Mean Volume of NaOH used in titration (titre) cm3 ±0.1cm3 6.63 4.10 8.39

3.3 Calculation of Processed Data The balanced equation for the reaction is: -

NaOH(aq) + HCl (aq)

NaCl(aq) + H₂O (l)

Moles of HCl present 500 x 0.1 =0.05 1000 Ratio of HCl: NaOH = 1:1 5 g of antacid was then dissolved in the HCl solution.

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Sample Calculation Gaviscon 0.05 Moles of HCl present in 500 cm3 A 10cm3 sample of Gaviscon dissolved in HCl was used to titrate against NaOH. Moles of NaOH used 6.63 ⁴ of NaOH x 0.1=6.63 x 1 ¯0moles 1000 Mole Ratio of HCl: NaOH = 1:1 Therefore, 6.63 x 1 0¯ ⁴ moles of HCl are present in the 10cm3 sample used. 4 6.63 x 1 0¯ =10 cm 3 x=500 cm 3 6.63 x 1 0¯4 x 500 /10 = 0.03315 moles used. Initial Moles of HCl present = 0.05 Moles left = 0.03315 Moles used = 0.05− 0.03315=0.01685 Percentage used: 0.05−0.01685 x 100= 66.3% 0.05 Similar calculations were done for the other two antacid tablets, to obtain: Antacid Moles Left Moles Used Percentage Used Gaviscon

0.03315 0.01685

66.3%

0.0205 0.0295

Eno Maalox Percentage Error

8.05 x 1 0¯3

0.04195

41.0% 83.9%

Antacid

Percentage of HCl used

Gaviscon

66.3%

Percentage Error 66.3 x 1.51=1.0 % 100

Maalox

83.9%

83.9 x 1.20 =1.0 % 100

Eno

41.0%

41.0 x 2.44 =1.0 % 100

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3.4 Interpretation of Data Effectiveness of Antacid 90.00% 80.00% 70.00% 60.00% 50.00% 40.00% 30.00% 20.00% 10.00% 0.00%

Gaviscon

Maalox

Percentage of HCl Neautralized

Eno

Mass of CaCO3 present

Figure 1 – Bar Graph showing correlation between acid neutralized and mass of CaCO₃ present

Based on the figure above, a negative correlation can be seen between the mass of Calcium Carbonate present, and the amount of HCl that can be neutralized. The calculations above as well, show that Maalox neutralized 83.9% of the acid, while Gaviscon neutralized 66.3%, showing that the most effective antacid would be Maalox. The mass of CaCO₃ in Eno, was the highest, having 855 mg, however the tablet neutralized just 41.0% of HCl present. This may be due to the lack of other effective ingredients in comparison to Maalox. The other ingredients present in Maalox are aluminum hydroxide, magnesium hydroxide and simethicone while Eno contains sodium carbonate, Sodium bicarbonate and citric acid. Gaviscon contains sodium alginate and sodium bicarbonate aside from calcium carbonate. This then as well shows that Calcium Carbonate being the active ingredient, may have the least effect within the antacids, as Maalox, which has the least amount of it, is effective to a large extent, neutralizing up to 83.9%. The final PH was 10 or above for all the antacids, due to the addition of NaOH which is a strong base. Therefore, adequate neutralization would be able to be observed when the PH is at 10, rather than 7.

4.0 Conclusion In conclusion, based on the data acquired from this experiment, the Maalox tablets are the most efficient in ensuring acidity is reduced within the stomach. This is because of the active

11 ingredients present within the antacid, where Calcium Carbonate, Aluminium Hydroxide and Magnesium Hydroxide all work efficiently in ensuring that up to 83.9% of HCl is neutralized, and the stomach PH is regulated. As shown in figure 1, Maalox had the least amount of Calcium Carbonate, which then nullifies my hypothesis, as I had stated that I thought that Eno, being the antacid with the most mass of CaCO₃ will be the most effective in its neutralizing ability. However, after conducting the experiment, I was able to determine that Calcium carbonate does not necessarily determine the effectiveness of the antacid, as it is the combination of all present ingredients. Eno used the least amount of volume of NaOH in neutralizing the acid (1.29 cm³), however it was the least effective at doing so, leaving behind almost 60% of acid within the stomach. Therefore, to answer my research question, Maalox is the most effective antacid, followed by Gaviscon and lastly Eno. Regardless of the hypothesis being incorrect, the results obtained his were accurate and were sufficiently and positively supported by the raw data obtained. Therefore, based on the results and the knowledge that all tablets used were within the range of a healthy dose for an adult (2 tablets), purchasing Maalox would be the most preferred solution as it is both economically efficient, and is an effective antacid in relieving pain.

4.1 Sources of Error and Improvements From the percentage uncertainties calculated above, uncertainties of the measurements used in the titration were approximately 4% in total, which yet again denoted that they were mediocrely low, which then further proves the validity of the conclusions that were derived from it. Small error bars, as shown on figure two, show the accuracy in the results being of minimal difference. Within the experiment, parallax errors could have been made when measuring the volumes of the sodium hydroxide & when reading the volume of sodium hydroxide added. Multiple other factors within the experiment contributed positively and negatively to the final results. Source of Error Random Error – Temperature was assumed to be constant as the experiment was being conducted within the school lab. Random Error – 3 trials were done for the experiment.

How it could affect the final result Fluctuations in surrounding temperature may cause a change in the rate of the reaction as well as the mechanism in which the two reactants react, causing inaccurate readings. An inaccurate average may be obtained as three trials may not be

Suggested Procedural Improvement A thermometer may be placed within the conical flask before and after the experiment, to ensure no temperature changes have occurred, as temperature is not a variable within the experiment. Increase number of trials conducted.

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Systematic Error – Use of PH meter caused fluctuations in results which may have given varying results that were not accurate. Systematic Error – Due to the PH levels increasing rapidly, a small amount of NaOH resulted in swift changes in PH, causing inaccurate shifts in PH. Systematic Error - reading meniscus from above rather than direct.

sufficient for a conclusion. Inaccurate reading of the PH as fluctuations occur.

Rinse the PH probe with distilled water after each trial to ensure lack of any impurities present.

Readings that were taken were not entirely similar in time taken to neutralize, which allows a conclusion to be formed without entire accuracy.

Maintain intervals of volumes added and ensure attention is kept on the PH levels after each interval.

Inaccurate readings.

Use equipment with uncertainty levels that are low to ensure accuracy in reading.

References Acid-Alkali Volumetric Titrations Calculating Concentrations from Experimental Results, Apparatus, Indicator, Conical Flask, Pipette, Burette Gcse Chemistry Calculations Antacid Indigestion Tablet Igcse KS4 Science A Level GCE AS A2 O Level Practice Questions Exercises, docbrown.info/page04/4_73calcs12vct.htm. Jecinta M. Experimental Data: 11.11 - Absolute and Percentage Uncertainty, 25 Aug. 2015, www.ibchem.com/IB16/11.16.htm. “Kognity.” App, 13 Mar. 2016, app.kognity.com/study/app/chemistry-hl-2016/option-dmedicinal-chemistry/ph-regulation-of-the-stomach/neutralisation-...