Chem Project

Background information What do stomach juice and anti-acid tablet contain? Stomach juice mainly contains Hydrochloric acid. Anti-acid tablet mainly contains Aluminium Hydroxide and Magnesium Hydroxide. Why Aluminium and Magnesium Hydroxide are being commonly used instead of other hydroxides? Other hydroxides may be poisonous(e.g. Zinc Hydroxide)or acts as a very strong alkali(e.g. Potassium Hydroxide). Since the neutralization between strong acid(Hydrochloric acid) and strong alkali is a exothermic reaction, it may cause even more serious burn in the patient's body. What is happening when we are getting a stomachache? When too much stomach juice(containing mostly acid) is secreted, heartburn will present and burns the esophagus. How does the anti-acid tablet work? When the tablet is taken in, molecules in the tablet soak up the hydrogen ions(produced from the ionization of the Hydrochloric acid) in stomach juice, and relieve the pain of heartburn. Antacids soak up hydrogen ions, so are “against acid”. We say they “neutralize” the acid. What is neutralization? Neutralization is a chemical reaction (also called a water forming reaction since a water molecule is formed during the process) in which an acid and a base or alkali (soluble base) react to produce salt and water (H2O). During the process, hydrogen ions H+ (a bare proton) from the acid or a hydroxide ion OH− or oxide ions O2− from the base react together to form a water molecule H2O. In the process, a salt is also formed when the anion from acid and the cation from base react together. For example, the reaction between Hydrochloric acid and sodium hydroxide solutions: hydrochloric acid + sodium hydroxide → sodium chloride + water HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) Ionic equation is: H+(aq) + Cl−(aq) + Na+(aq) + OH−(aq) → Na+(aq) + Cl−(aq) + H2O(l)

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Objective for the experiment To decide which brand of anti-acid tablets is the best buy, the price is considered first of all. As everyone knows, the cheapest one is brought for most as most people want to pay less. However, the price, of course, is not the only aspect to think of, the amount of anti acid in the tablets can also determine which one is the best buy. There is one thing we should learn that anti-acid tablets actually contain substances besides anti-acid which is alkaline hydroxide. If a tablet has more mole of alkaline hydroxide, the reaction rate of the tablet with the hydrochloric acid in the stomach can be faster and more acid can be neutralized which can help the patient to relieve the painfulness faster and more efficient. The efficiency of tablets is therefore proportional to the amount of anti acid. On the other hand, we would like to consider the ingredient too. As some active ingredient like carbonate, would cause the patient to have some gases produced in the stomach. (Equation: CO3- + H+  H20 + CO2) So we would like to consider this part also. It the last word, the brand of anti-acid tablets with the lowest price and largest amount of anti acid would be the best buy with the active ingredient that won’t cause the patient any other troubles. On the other hand, we would then find out the experimental error, improvement and the problem we’ve meet in it so that we can perform better for the next time.

Information for the three brands of the anti-acid tablet 2

Fedra-Gel-S Chewable Tablet Each tablet contains: Aluminium Hydroxide Dried Gel 200mg, Magnesium Hydroxide 200mg, Simethicone 30mg Maalox Plus Each tablet contains: In this experiment, we are going to first dissolved the Then we carry out titration, by Mg(OH)2 200 mg,We dried Al(OH)3 gel 225 mg, simethicone 25 mg find out which brand, among 3 anti-acid tablet powder adding NaOH to the remains Mas brands, Each is the best buycontains: anti-acid in 25cm3 HCL, which HCl, to find out how much acid tablet tablet. delivered by a 25cm3 is Hydroxide needed for reacting with Aluminium Hydroxide 200mg, Magnesium 150mg, hydroxide in tablet. Simethicone 25mgpipette. And boil it to let it dissolved more efficiently.

Ideas behind the experiment As we know that, the active ingredient in the tablet is aluminum hydroxide and magnesium hydroxide. They are insoluble in water that we can’t make a complete solution just by adding water. So we added the excess HCl to react with it. Equation: Mg(OH)2 + HCl → MgCl + H2O Al(OH)3 + 3HCl → AlCl3 + 3H2O After they become soluble, the left H+ ions with then react with NaOH. Equation:

HCl + NaOH → NaCl + H2O

Then we can find the mole number of excess HCl after the reaction between the HCl and NaOH by titration. Which in turn we can find out the mole number of the active ingredient.

Summary of the procedures in experiment 3

An orange colour of methyl orange indicates the end point.

By the result of NaOH used and the amount of anti-acid tablet used , we can find out the mole of hydroxide in tablet. So we can determine which one is the best buy brand by looking for the largest mole among 3 different brands’ tablets.

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Result in the experiment For the brand Fedra-Gel-S Chewable Tablet, 5

Reading\Trial 1 Initial 2.5 Final 15.4 Volume decrease (cm3) 12.9 Amount of anti-acid(g) 0.76 Average volume of NaOH used = 13.50cm3 Average amount of tablet used = 0.79g

2 16.7 30.9 14.2 0.81

3 31.5 44.9 13.4 0.79

An ionic equation for the reaction in the conical flask during titration: OH − + H + → H 2 O Number of mole of NaOH = 1*13.5/1000 = 0.0135mole Number of mole of OH − = 0.0135mole Mole of OH − : mole of H+ = 1:1 Number of mole of H+ = 0.0135mole An ionic equation for the reaction in the conical flask when the anti-acid tablet dissolves in the HCl: OH − + nH + → H 2 O + (n − 1) H + Number of mole of H+ in HCl = 1*25/1000 = 0.025mole Number of mole of (n-1)H+ = 0.0135mole Number of mole of H+ being neutralized = 0.025-0.0135 = 0.0115mole Number of mole of H+: number of mole of H2O = 1:1 Number of mole of H2O = 0.0115mole Number of mole of OH − : number of mole of H2O = 1:1 Number of mole of OH − = 0.0115mole According to the label of the tablet, Amount of Al(OH)3: Amount of Mg(OH)2 = 200mg:200mg = 1:1 Al (OH ) 3 + Mg (OH ) 2 + 5 HCl → AlCl 3 + MgCl3 + 5 H 2 O Number of mole of Al(OH)3: Number of mole of H2O = 1:5 Number of mole of Al(OH)3 = 0.0023mole Amount of Aluminium Hydroxide = 0.0023*(27+(16+1)*3) = 0.0023*78 = 0.1794g Number of mole of Mg(OH)2: Number of mole of H2O = 1:5 Number of mole of Mg(OH)2 = 0.0023mole Amount of Magnesium Hydroxide = 0.0023*(24.3+(16+1)*2) = 0.0023*58.3 = 0.1341g Total amount of active ingredient = 0.1794g + 0.1341g = 0.3135g Amount of active ingredient per gram of tablet = 0.3135g/0.79g = 0.397g Number of mole of OH − per gram of tablet = 0.0115mole/0.79g = 0.0146moleg-1

For the brand Maalox Plus Tablet,

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Reading\Trial 1 Initial 23.5 Final 38.3 Volume decrease(cm3) 14.8 Amount of anti-acid(g) 1.22 Average volume of NaOH used = 14.7cm3 Average amount of tablet used = 1.20g

2 28.5 43.1 14.6 1.17

3 0.2 15 14.7 1.2

An ionic equation for the reaction in the conical flask during titration: OH − + H + → H 2 O Number of mole of NaOH = 1*14.7/1000 = 0.0147mole Number of mole of OH − = 0.0147mole Mole of OH − : mole of H+ = 1:1 Number of mole of H+ = 0.0147mole An ionic equation for the reaction in the conical flask when the anti-acid tablet dissolves in the HCl: OH − + nH + → H 2 O + (n − 1) H + Number of mole of nH+ in HCl = 1*25/1000 = 0.025mole Number of mole of (n-1)H+ = 0.0147mole Number of mole of H+ being neutralized = 0.025-0.0147 = 0.0103mole Number of mole of H+: number of mole of H2O = 1:1 Number of mole of H2O = 0.0103mole Number of mole of OH − : number of mole of H2O = 1:1 Number of mole of OH − = 0.0103mole According to the label of the tablet, Amount of Al(OH)3: Amount of Mg(OH)2 = 225mg:200mg = 9:8 9 Al (OH ) 3 + 8Mg (OH ) 2 + 42 HCl → 9 AlCl 3 + 8MgCl 2 + 42 H 2 O Number of mole of Al(OH)3: Number of mole of H2O = 9:42 Number of mole of Al(OH)3 = 0.00221mole Amount of Aluminium Hydroxide = 0.00221*(27+(16+1)*3) = 0.00221*78 = 0.1722g Number of mole of Mg(OH)2: Number of mole of H2O = 8:42 Number of mole of Mg(OH)2 = 0.00196mole Amount of Magnesium Hydroxide = 0.00196*(24.3+(16+1)*2) = 0.00196*58.3 = 0.1144g Total amount of active ingredient = 0.1722g + 0.1144g = 0.2866g Amount of active ingredient per gram of tablet = 0.2866g/1.20g = 0.239g Number of mole of OH − per gram of tablet = 0.0103mole/1.20g = 0.00858moleg-1

For the brand Mas Tablet,

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Reading\Trial 1 Initial 18 Final 29 Volume decrease(cm3) 14.2 Amount of anti-acid(g) 0.58 Average volume of NaOH used = 15.2cm3 Average amount of tablet used = 0.60g

2 14.8 28.7 16.5 0.62

3 15 31.5 14.9 0.59

An ionic equation for the reaction in the conical flask during titration: OH − + H + → H 2 O Number of mole of NaOH = 1*15.2/1000 = 0.0152mole Number of mole of OH − = 0.0152mole Mole of OH − : mole of H+ = 1:1 Number of mole of H+ = 0.0152mole An ionic equation for the reaction in the conical flask when the anti-acid tablet dissolves in the HCl: OH − + nH + → H 2 O + (n − 1) H + Number of mole of H+ in HCl = 1*25/1000 = 0.025mole Number of mole of (n-1)H+ = 0.0147mole Number of mole of H+ being neutralized = 0.025-0.0147 = 0.0103mole Number of mole of H+: number of mole of H2O = 1:1 Number of mole of H2O = 0.0103mole Number of mole of OH − : number of mole of H2O = 1:1 Number of mole of OH − = 0.0103mole According to the label of the tablet, Amount of Al(OH)3: Amount of Mg(OH)2 =200mg:150mg = 4:3 4 Al (OH ) 3 + 3Mg (OH ) 2 + 18 HCl → 4 AlCl 3 + 3MgCl 2 + 18 H 2 O Number of mole of Al(OH)3: Number of mole of H2O = 4:18 Number of mole of Al(OH)3 = 0.00229mole Amount of Aluminium Hydroxide = 0.00229*(27+(16+1)*3) = 0.00229*78 = 0.1785g Number of mole of Mg(OH)2: Number of mole of H2O = 3:18 Number of mole of Mg(OH)2 = 0.00172 Amount of Magnesium Hydroxide = 0.00172*(24.3+(16+1)*2) = 0.00172*58.3 = 0.1003g Total amount of active ingredient = 0.1785g + 0.1003g = 0.2788g Amount of active ingredient per gram of tablet = 0.2788g/0.60g = 0.465g Number of mole of OH − per gram of tablet = 0.0103mole/0.60g = 0.0172moleg-1

Results and comparisons 8

After calculations, the results are organized and presented into table. Brand Amount of tablet used (g) Number of mole of OH − in amount used Number of mole of OH − per gram of tablet (moleg-1) Amount of active ingredient (g) Amount of active ingredient per gram of tablet (g) Price of one tablet ($) Number of mole of OH − per one dollar (mole per dollar) Amount of active ingredient per one dollar (g per dollar)

Fedra Gel-S 0.79 0.0115

Maalox Plus 1.20 0.0103

Mas 0.60 0.0103

0.0146

0.00858

0.0172

0.3135 0.397

0.2866 0.239

0.2788 0.465

1 0.0115

2 0.00515

0.5 0.0206

0.3135

0.1433

0.5576

From the above table, we may easily find the amount of the active ingredient in different brands of anti-acid tablets are not the same as labeled. It may due to the experimental error, but now we are going to discuss how they are different from the label. In the brand Fedra Gel-S Chewable tablet, the manufacturer claimed that there are 200mg of aluminium hydroxide dried gel and 200mg of magnesium hydroxide as the active ingredients. However, based on our experimental result, there are only 179.4mg (0.1794g) of aluminium hydroxide and 134.1mg (0.1341g) of magnesium hydroxide. There is totally 313.5mg (0.3135g) of active ingredient in the tablet, not as claimed 400mg. In the brand Maalox Plus tablet, the manufacturer claimed that there are 225mg of dried aluminium hydroxide gel and 200mg of magnesium hydroxide as the active ingredients in the tablet. However, based on experimental result, there are only 172.2mg (0.1722g) of aluminium hydroxide and 114.4mg (0.1144g) of magnesium hydroxide. There are totally 286.6mg (0.2866g) of active ingredient in the tablet, not as claimed 425mg of active ingredients. In the brand Mas tablet, the manufacturer claimed that there are 200mg of aluminium hydroxide and 150mg of magnesium hydroxide as the active ingredients in the tablet. However, based on our experimental result, there are only 178.5mg (0.1785g) of aluminium hydroxide and 100.3mg (0.1003g) of magnesium hydroxide. There are totally 278.8mg (0.2788g) of active ingredients in the tablet, not as claimed 350mg of active ingredients. In conclusion, it seems Fedra Gel-S Chewable tablet has more amounts of active ingredients in the tablet, but we need to consider the brands with their sizes and prices. Fedra Gel-S has more amounts of active ingredients in the tablet with medium size and price. Maalox Plus has the medium amounts of active ingredients but larger in size and cost more. Mas has the least amounts of active ingredients with the smallest size and cost less. By comparing with the sizes and prices of them (you may refer to the above table), it is easily to determine that Mas is the best buy.

Conclusion

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As what we said in the objective, we would based on three things to find out the best-buy brand which is: 1) price As we can see in the chart, the cheapest brand is Mas. It only courses 0.5 dollars for one tablet. While the highest one is Maalox Plus that it couses 2 dollars. If we look at the size, we would find that the size of Mas is the smallest. This could be the reason why it is so cheap. Therefore we can still determine whether it is best buy or yet.

Price of one tablet ($) 2 1.5 1

Price of one tablet ($)

0.5 0 Fedra Gel-S

Maalox Plus

Mas

2) The amount of active ingrediant If the price can’t help us to make the right choice, then we compare the amount of the active ingredient per one dollar. From the chart we can see that the highest amount of active ingredient is Mas again while the smallest one is Maalox Plus. The amount of the active ingredient is important as this ingredient would react with HCl in our stomach. So the highest amount of active ingredient mean our painfulness could be treated at a faster rate. If we compare the price with the number of the mole of active ingredient per one dollars, we could still find that Mas has the highest of all with Maalox Plus the lowest again. Number of mole of per one dollar (mole per dollar)

Amount of active ingredient per one dollar (g per dollar) 0.6

0.025

0.5

0.02

0.4

0.015

0.3

Amount of active ingredient per one dollar (g per dollar)

0.2

0.005

0.1 0

Number of mole of per one dollar (mole per dollar)

0.01

Fedra Gel-S

Maalox Plus

Mas

0

Fedra Gel-S

Maalox Plus

Mas

3) the side effect ingredient in the three brands, the active ingredient is the same with Aluminium hydroxide and Magnesium Hydroxide. The alkaline hydroxide has no side effect to the human body as product produced is not poisonous nor would produce any gases or solid too. But there are two brands has other component for Maalox Plus and Fedra-gel-S. they are yellow in colur as they has added some chemical to give out smell like lemon. But they are not harmful to human body. Final comparison of the three brands( = the best) Fedra-gel-S Maalox Plus Mas price The amount of active ingrediant the side effect ingredient From the table, we can then determine that Mas has the cheapest price and the largest amount of the active ingredient. So the best-buy brand is: Mas!

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Problem meet in experiment There are two main problems we have meted when we were doing the experiment. 1) The anti-acid tablet was not all dissolved in HCl. As what we have planned to do was that we expected the tablet would react with excess HCl and no solid should be left in the beaker. But it turns out that there were some little solid still in the beaker. This may affect the result as the weight we measure is not the same as the weight of tablet that underwent the reaction. So starting from second trail, we added two more procedure. When we poured HCl into the tablet, we added the distilled water at the same time and stirred it quickly. This can made the powder to dissolve more easily and prevent the large solid formed. Then we heated it with Bunsen burner. We didn’t heat it for a long time. We just heat it before the solution reaches the boiling point. This was to dissolve the little solid left. After we doing this, the condition was much better. Only a very small amount of it left. Maybe these are other substance in the tablet other than hydroxide. 2) Colour of tablet In two of the three types of the tablets, it has the yellow colour. The solution dissolved was also yellowish. This made us hard to observe after dropping the 2 drops of methyl orange and the end point was in the similar colour. To make a better observation, 8 drops of methyl orange were added. The advantage was that 8 drops of methyl orange can cover the yellow colour and the colour change when titrating was obvious. 3) Different mass of the same brand of the tablets As we crushed the tablet and then measure the used amount of the tablet, it appeared as different mass of it. We can’t just refer to the first trail to get the approximate amount of NaOH to be used in the second trail. Based on this problem, we didn’t take the second and third trail for calculation only, but also the first trail. so the average mass we get for the tablet is included with all the trails.

Experimental error Reading error When we are taking the values in pipette and burette, the value that we took may not be the same as the actual one. Therefore we tried to read the result by more than one person and read the result in eye level. Reaction time It was hard to stop the running of NaOH right at the end point during titration. There will be the time needed for us to react and turn the stopcock. However, the volume of excess NaOH was approximately similar. That the error could cancel each other. Solubility The tablet powder was not totally disappeared when HCl was added. Although we have taken some action to reduce the problem, the weight we took and the weight that reacted with was still different. Improvement could be made next time. That all of the powder should not be added immediately. Because the powder may float on the surface of HCl caused by tension. So we should add the powder with the small amount each time and stir the solution frequently.

Improvement 11

1. when we add the HCl to the powder, we can add distilled water to it also. This is because distilled water allowed anti-acid tablet to react with HCl better. And powder may float on the surface of the HCl. So that we should pour distilled water and HCl and stir the solution to prevent the floating of the powder and a large solid granule formed. 2. Take the reading of the liquid level in the pipette and burette at eye level because a small difference between the reading and the actual value will cause an inaccurate result. 3. prepare more conical flasks. As we are doing the experiment, we may like to prepare the next tablet at the same time. But the lack of the flask limits our action and we can’t save more times. 4. a little powder sticked on the wall of the beaker. This affect the accurate weight we take by the balance. The improvement method may refer to point 1. Further investigation In our three chosen brands, the active ingredient is the same. And they will work similarly. We would like to investigate the other brands of the drugs which are having the different ingredient like CaCO3 or Ca(OH)2. as they have the similar effect towards the neutralizing power, it will be better for us to choose the different active ingredient for the investigation. On the other hand, we may want to know the truth of the most expensive and most cheapest brand and find out whether the price is directly proportional to the power. Because based on our result, Mas with the cheapest has a more powerful ability. So we can show at the same time whether the statement for the more expensive one has a better performance. Duty list Name Abby

Isabella

Gloria

Duty -write problem meet in experiment - writing conclusion and further investigation -editing the project - writing the definition for what should be a best buy antiacid - responsible for art decoration -writing result and responsible for calculation -write for the comparison of the three brands.

Peony

- summary of the procedure -write experimental error and improvement for it.

Christine

-buying the 3 brands of anti-acid - collect and writing the background information -taking photographs

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