How Much Aspirin Can I Make PDF

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Chemistry Lab Report Experiment 5: How Much Aspirin Can I Make?

February 19, 2021 Spring 2021

02/26/2021

I. Introduction A reaction stoichiometry is a numerical relationship that can be taken into consideration between reactants and products in a balanced equation, this is also known as molar ratios in a chemical equation. Reaction Stoichiometry will give the amount of reactant that was used in a particular equation as well as the moles that are formed from a specific balanced equation. The limiting reagent is the one that will control the amount of the product that will be produced in a chemical reaction, this is because the limiting reagent is the one that will be totally consumed. Now, the excess reagent is the one that has more than enough and is the reagent that is not completely consumed in the reaction. In this specific experiment, the objectives in this experiment were to the concepts of limiting and excess reagent to synthesize an aspirin sample, also to classify the type of aspirin reaction. To later, be able to calculate the percent yield and to evaluate the purity and the quantity of the aspirin by using the melting point. These objectives were accomplished by applying some problem-solving. In this experiment, the reaction stoichiometry was applied in the synthesis of aspirin since the reaction was a chemical equation and the relationship between the reactant and the product was being determined to identify the quantitative results. In order to determine the amounts of limiting and excess reagent with stoichiometry in this experiment, the quantities values that were given were the ones that it was used, which were the mass and the volume, and an assigned amount of excess reagent and a ratio mole that was used in the conversation to identify the quantitative grams used. However, in order to do this calculation, it is extremely important to have a balanced chemical equation first before doing stoichiometry calculations because mass is conserved and it is the only way it can be predicted the amount of reactant that is needed or the amount of the product that can be produced. This is because the number of types of atoms has to be the same on each side of the reaction, in the reactant, and in

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the product. In order to prevent any errors in the lab when synthesizing aspirin, there were many lab techniques that needed to be followed, and some of them were to carefully, and property use the hot plate and the vacuum filtration. Also, to determine the purity of the synthesized aspirin, this was accomplished by measuring the melting point range once this was calculated compared to the theoretical value to calculate the percent error. In this specific experiment, there were a lot of procedural and chemical hazards that were identified before performing the experiment. The hazards and safety precautions in this experiment were carefully handling phosphoric acid, acetic anhydride because acetic anhydride will irritate eyes and will also cause a burn to the skin, and hot objects while wearing the appropriate PPE. More precautions were keeping the cable away from the hot plate, washing hands, and securing the apparatus tightly in the vacuum filtration. Procedure: See Lab Procedure. II. Results Analysis PART I Planning and Carrying Out the Synthesis of Aspirin

A. Stoichiometric Calculations: 𝑔 3.0 mLC4H6O3×1.08 𝑚𝐿 = 3.24g C4H6O3

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3.24g C4H6O3 ×

1 𝑚𝑜𝑙𝑐4𝐻6𝑂6 102𝑔𝑐4𝐻6𝑂6

×

1𝑚𝑜𝑙𝑐7𝐻6𝑂3 1𝑚𝑜𝑙𝑐7𝐻6𝑂3

1𝑚𝑜𝑙𝑐7𝐻6𝑂3

138𝑔𝑐7𝐻6𝑂3

× 1.5𝑚𝑜𝑙𝑐 𝐻 𝑂 × 1𝑚𝑜𝑙𝑐 𝐻 𝑂 7

6 3

7

=

6 3

2.92g𝐶7𝐻6𝑂3 Synthesis code assigned by the instructor

Code C

Percent of excess Acetic Anhydride (AA)

50%

The mole ratio of AA to Salicylic Acid (SA)

1.5 moles

Given volume AA

3 mL

The calculated mass of SA

2.92g Table 1

B. Aspirin Synthesis

× 3

2.92g𝐶 𝐻 𝑂 7

6

1 𝑚𝑜𝑙𝑐7𝐻8𝑂3 138𝑔𝑐7𝐻8𝑂3

×

1 𝑚𝑜𝑙𝐶9𝐻8𝑂4 1𝑚𝑜𝑙𝑐7𝐻8𝑂3

180𝑔𝐶 𝐻 𝑂

× 1𝑚𝑜𝑙𝐶9𝐻8𝑂4 = 3.81g𝐶9𝐻8𝑂4 9

8 4

Mass of SA used

2.92g

The volume of AA used

3 mL

Mass of AA used (volume x 1.8 g/mL)

3.24 g

Theoretical Yield of Aspirin

3.81g Table 2

Observation during the reaction (briefly describe) After it was mixed it was white precipitation but after it was heated in hot water the reaction turned a yellowish-brown liquid reaction. k. Physical properties of dry aspirin (briefly describe): It was a white, crystalline substance. Part I B calculations Mass of dry Aspirin → 4.340g -1.720g = 2.620g

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Percent yield =

2.620 × 100 = 68.7% 3.811 Code C

What type of reaction is synthesizing aspirin?

Esterification

Mass of filter paper + foil + dry aspirin (first weighing) (D.1)

4.340g

Mass of filter paper + foil + dry aspirin (second weighing) (D.2)

4.339g

Mass of filter paper + foil (D.3)

1.720g

Mass of dry Aspirin (Actual yield = (D.1)-(D.3))

2.620g

𝐴𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑

Percent yield = 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 × 100

68.7% Table 3

PART II Melting Point Determination Code C Observed melting temperature range (D.4)

130-137 °C

Theoretical Melting Point Range of Aspirin

138 - 140°C Table 4

(Link reference: https://pubchem.ncbi.nlm.nih.gov/compound/Aspirin.) Summary of Important Results Group code A(200% Excess AA)

Percent Yield 87.5%

Melting Point Range (oC) 125-140 °C

B (100% Excess AA)

80.6%

127-138 °C

C (50% Excess AA)

68.7%

130-137 °C Table 5

1. Which Synthesis Code gives the highest percent yield? Code A gives the highest percent yield. 2. Based on the melting point results, which Synthesis Code gives a high purity aspirin? Explain why?

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Based on the melting point results, the code that gives the high purity aspirin is code C, this is because the melting point of the aspirin is higher than smaller than any other code. Therefore it was closer to the actual melting point of aspirin.

3. What are the possible reasons for your low or high percentage yield, and low or high aspirin purity? There was a pattern in the percent yield and the melting point. While the percent yield of the aspirin was closer to 100% the melting point range increased making aspirin impure but when the percent yield decreased the melting point of the range of the melting point increased. One possible reason for this could be that the aspirin still had insoluble impurities in it. This simply indicated that the insoluble impurities cause a melting point depression having a higher percent yield.

4. Based on your answers to the Data Analysis Questions, which percent excess acetic anhydride will you use in Part III? Briefly explain why? For part III, I will use 50% excess acetic anhydride (Code C) because I will not get too much excess acetic anhydride, which will allow making sure that all the salicylic acid is used since it is the most expensive out of the two, it is important not to waste any of the two. Although I will not get 100% yield, I will be able to make pure and quality because with a little percent access of acetic anhydride the purity of the aspirin is better than using a higher percentage of the excess.

Part III Limiting and Excess Reactants Concept Application

b) 325

1𝑔 2000 𝑡𝑎𝑏𝑙𝑒𝑡 𝑚𝑔 × × = 650g𝐶9𝐻8𝑂4 1 𝑡𝑎𝑏𝑙𝑒𝑡 1000𝑚𝑔

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c) 650g𝐶9𝐻8𝑂4 ×

e) 650g𝐶9𝐻8𝑂4

1 𝑚𝑜𝑙𝐶9𝐻8𝑂4

1 𝑚𝑜𝑙𝑐7𝐻6𝑂3

× 1𝑚𝑜𝑙𝐶 𝐻 𝑂 × 1𝑚𝑜𝑙𝑐 𝐻 𝑂

180𝑔𝐶9𝐻8𝑂4

1 𝑚𝑜𝑙𝐶9𝐻8𝑂4 180𝑔𝐶9𝐻8𝑂4

138𝑔𝑐7𝐻6𝑂3

9

8 4

1𝑚𝑜𝑙𝑐 𝐻 𝑂

× 1𝑚𝑜𝑙𝐶4 𝐻6 𝑂3 × 9

8 4

7

= 498g𝐶7𝐻6𝑂3

6 3

1.5𝑚𝑜𝑙𝑐4𝐻6𝑂3 1𝑚𝑜𝑙𝑐4𝐻6𝑂3

102𝑔𝑐 𝐻 𝑂

× 1𝑚𝑜𝑙𝑐4𝐻6𝑂3 = 4

6 3

552g𝐶4𝐻6𝑂3

d) 552g𝐶 𝐻 𝑂 4

6 3

1𝑚𝐿𝐶4𝐻6𝑂3

× 1.08𝑔𝐶 𝐻 𝑂

f) Unit cost of SA

4

6 3

= 511 mL 𝐶 𝐻 𝑂 4 6 3

133.46 = $0.27 498

g) Unit cost of AA

164.22 = $0.30 552

j) Cost of 2000 tablets $164.22 + $133.46 = $297.68 a. Number of tablets (325 mg/tablet

2000

b. Target theoretical yield

650g

c. Mass of salicylic acid (limiting reagent) needed

498g

d. The volume of acetic anhydride needed

511mL

e. Mass of acetic anhydride needed (volume x 1.08g/mL)

552g

f. Unit cost of salicylic acid ($/g)

0.27$/g

g. Unit cost of acetic anhydride ($/g)

0.30$/g

h. The total cost of salicylic acid ($)

$133.46

i. The total cost of acetic anhydride ($)

$164.22

j. The total cost to make 2000 tablets ($)

297.68

Table 6 Note: Shipment cost was neglected. 552gAA = $164.22

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498gSA = $133.46 A. Data and Calculations for excess 200% and 100% 𝑔

A) 3.0 mLC4H6O3× 1.08 𝑚𝐿 = 3.24g C4H6O3

3.24g C4H6O3 ×

1 𝑚𝑜𝑙𝑐4𝐻6𝑂6 102𝑔𝑐4𝐻6𝑂6

×

1𝑚𝑜𝑙𝑐7𝐻6𝑂3 1𝑚𝑜𝑙𝑐7𝐻6𝑂3

1𝑚𝑜𝑙𝑐7𝐻6𝑂3

138𝑔𝑐7𝐻6𝑂3

× 3 𝑚𝑜𝑙𝑐 𝐻 𝑂 × 1𝑚𝑜𝑙𝑐 𝐻 𝑂 7

6 3

7

=

6 3

1.46g𝐶 𝐻 𝑂 7

6 3

1.46g𝐶7𝐻6𝑂3×

Percent yield =

1 𝑚𝑜𝑙𝑐7𝐻8𝑂3 138𝑔𝑐7𝐻8𝑂3

×

1 𝑚𝑜𝑙𝐶9𝐻8𝑂4 1𝑚𝑜𝑙𝑐7𝐻8𝑂3

180𝑔𝐶 𝐻 𝑂

× 1𝑚𝑜𝑙𝐶9𝐻8𝑂4 = 1.90g𝐶9𝐻8𝑂4 9

8 4

1.662 × 100 = 87.5% 1.90 𝑔

B) 3.0 mLC4H6O3× 1.08 𝑚𝐿 = 3.24g C4H6O3

3.24g C4H6O3 ×

1 𝑚𝑜𝑙𝑐4𝐻6𝑂6 102𝑔𝑐4𝐻6𝑂6

×

1𝑚𝑜𝑙𝑐7𝐻6𝑂3 1𝑚𝑜𝑙𝑐7𝐻6𝑂3

1𝑚𝑜𝑙𝑐 𝐻 𝑂

138𝑔𝑐 𝐻 𝑂

× 2 𝑚𝑜𝑙𝑐7 𝐻6 𝑂3 × 1𝑚𝑜𝑙𝑐7𝐻6𝑂3 7

6 3

7

=

6 3

2.19g𝐶7𝐻6𝑂3

2.19g𝐶7𝐻6𝑂3×

Percent yield =

1 𝑚𝑜𝑙𝑐7𝐻8𝑂3 138𝑔𝑐7𝐻8𝑂3

×

1 𝑚𝑜𝑙𝐶9𝐻8𝑂4 1𝑚𝑜𝑙𝑐7𝐻8𝑂3

180𝑔𝐶9𝐻8𝑂4

× 1𝑚𝑜𝑙𝐶 𝐻 𝑂 9

8 4

= 2.86g𝐶9𝐻8𝑂4

2.305 × 100 = 80.6% 2.860

Additional Calculations for the cost of AA and SA

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To determine the total cost of grams, for a cheaper product some important decisions were made, and some calculations as shown below. The cost of SA was $134 per 500g in order to determine how much money it was needed, the following calculations were made,

𝑆𝐴

134 = $0.536/2g → $134- 0.536 = $133.46 250

2 grams of SA were subtracted because the amount needed was 552g. For AA the price of the reagent was $119 every 400g and because 552g were needed, the following calculations were made to find the price of 552g. Solve for x in the equation below 400𝑥 = (119 × 552) simple algebra, multiply inside the parenthesis 400𝑥 = 65688 from here, divide by 400 x=

65688 400

x = 164.22 Therefore the total price of 552g of AA was $164.22. After collecting all the results from the experiment, it was important to bring up some of the important results that were collected since a lot of math was involved in this experiment in order to synthesize aspirin. In the first part of the experiment, there was a certain amount of reactant that was given which was 3mL as well as 1.08 g/mL of acetic anhydride as indicated in Table 1. This was utilized as an excess reagent and the amount of excess that was used was 50% with a ratio of 1.5mol, as indicated in Table 1, this was then used to find the amount of salicylic acid, which was the limiting reagent. When the limiting reagent was found, stoichiometry was used to find the amount of product that was expected meaning the theoretical yield which was 3.81g of aspirin as reported in Table 2. After that, the amount of aspirin that was collected from the experiment was then weighed to obtain the actual yield which was 2.620g and the final

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percent yield was 68.7%. However, to get the actual yield some calculations needed to be done, these are shown in Table 3. This suggested that the results were not excellent but still a good percent yield. In the melting point range, there was not much of a difference as shown in Table 4, although the results were not the same the melting point range was almost the same. This was considered purity since the melting range point was not too off. When the percentage of acetic anhydride excess was higher, the percent yield was higher but the melting point range was higher as shown in Table 5. This suggested that with less excess of acetic anhydride the purity of aspirin was higher. Discussion Part I Planning and Carrying Out the Synthesis of Aspirin Based on the expected physical properties of products, the type of reaction to synthesize a sample of aspirin was the esterification reaction. This was accomplished by the balanced chemical equation that was, C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2 or

In this reaction, the limiting reactant was salicylic acid, and therefore the excess reactant was acetic anhydride. In this experiment, there were three synthesis codes that were assigned to different students. My assigned code was C which contained 50% excess acetic anhydride containing a mole ratio of 1:1.5 between the limiting and the excess reagent. Using

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stoichiometry, the theoretical yield was calculated and it was 3.81 grams of aspirin. Now, in order to synthesize aspirin, the synthesis apparatus was set up by heating the mixture of salicylic acid and anhydride on a hot plate, after that, the Buchner Funnel and the flask were set up for vacuum filtration. While performing the experiment, some chemicals indicators that were observed were the precipitation when salicylic acid and acetic anhydride were mixed, and later when heating it with hot water, it turned into a yellow-brown color. Another indicator of chemical change was the formation of precipitation once again when it was cooling down with ice. The mixture of the two reactants then turned into crystal-like structures once it was cold. After all the procedures were followed the mass of the weighted mass was 2.620 grams, which was the actual yield, this was compared to the theoretical yield, which gave a 68.7% yield. The probable reason for the low percent yield was because it was the one that used the lowest excess percentage of acetic anhydride.

Part II Melting Point Determination In the second part of the experiment, the melting point range was determined. The main purpose of the melting point was to determine how pure the sample of aspirin was. In order to determine the melting point a Melt-Temp apparatus was used which was then used to heat the capillary tube with aspirin at a high temperature. When the capillary tube was in the Melt-Tem there were some changes that indicated that the melting point was reached, this was accomplished by looking at the watch glass for the first sign when the aspirin sample started to melt and when the aspirin sample was completely melted, meaning when the solid turned into liquid. The two temperatures were recorded in order to get the melting point range, the first temperature when the sample started to melt was first noted at 130 degrees Celsius, and the temperature when the sample of aspirin was completely melted was at 137 degrees celsius.

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However, the theoretical melting point of aspirin according to the National Center for Biotechnology Information (2021), is from 138 to 140 degrees Celsius. The percent error of the melting point between the theoretical melting point and the actual melting point was 2.14%, considering when the melting point completely melted. Now, the percent error of the melting point when it first started melting was 5.80%. According to the results collected from the lab, the synthesis code that gave the highest percent yield was code A, now, the code that indicates the highest purity of aspirin was code C. Based on analysis question 1, the percent excess that was used was 50% for part III Part III Limiting and Excess Reactants Concept Application When preparing 2000 tables of aspirin at (325 mg/tablet) the theoretical yield was 650 grams of aspirin. Now, in order to make 650 grams of aspirin, 498 grams of salicylic acid and 552 grams of acetic anhydride were needed. Considering that code C was used with a mole ratio of 1:1.5. The total cost to make 2000 aspirin tablets was $297.68. By obtaining reasonable prices of chemicals, it was calculated that the cost of salicylic acid per unit was $0.27/g, and for the acetic anhydride, the price per unit was $0.30/g. The calculations for these prices can be found in Table 6. III. Conclusions In this experiment, as it was observed, there are many chemical applications to this specific experiment. Some common that are often studied in chemistry are synthesis reactions, stoichiometry reactions with limiting and excess reagent, the formation of precipitation, and the esterification reaction. When synthesizing aspirin and this was placed in cold water for the liquid to form solid, the formation of white crystals-shaped precipitate was observed. By calculating the melting point of the aspirin, the level of purity of the aspirin was determined and the

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experimental melting points supported the conclusion on the purity of your synthesized crystals because the closer the ranges of the melting point were, the aspirin sample was considered purer. The results from the three experiment indicated that the synthesis code that gave the highest percent yield was code A because it had the most acetic anhydride, however, when the percent yield was high then the sample of aspirin was less pure but the code that gave the highest purity out of all three was code synthesis code C because it had the least excess acetic anhydride and although it had the lowest percent yield, the produced aspirin purity was the highest, this was because it was the percent error between the melting point of the theoretical and the experimental value were the closest. To have a good quality of aspirin is better if there is less percentage of acetic anhydride, that way the percent error in the melting point is much less. Now for an excellent percent yield of aspirin more excess anhydride is required. Now, to have an average of the two, it is recommended code B which has a mole ratio of 1:2. A practical application of this experiment was using the data and the knowledge learned such as stoichiometry, theoretical yield, finding the limiting and the excess reagent to determine how much was needed to make a certain amount of tablets of aspirin as well as how much money was going to be spent in the total amount of chemicals needed as well as how much was spent per unit.

.

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Bibliography National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 2244, Aspirin. Retrieved February 21, 2021, from https://pubchem.ncbi.nlm.nih.gov/compound/Aspirin. Randall, J. (2007). Advanced chemistry with Vernier, third ...