Synthesis of Aspirin and Risk Assessment of the effects of antibiotics on bacterial growth
Introduction.
This experiment was performed via the esterification process to produce the crude aspirin and obtain the percentage yield of aspirin. In chemistry, aspirin is known as an organic ester, a compound that is produced from a reaction of an alcohol ( -OH group). In the production of aspirin, ethanoic anhydride reacts with 2- hydroxybenzenecarboxylic acid, which is simply salicylic acid to produce the ester itself. The excess of anhydride reacts with the water generated during esterification, moves the scale forward, and provides better performance for the desired project. A catalyst, usually sulfuric or phosphoric acid, is used to increase the rate of the reaction.(Cengage 91-94).
Procedure.
- Synthesis of crude aspirin.
Weigh 5.0 g of Salicylic acid (2- hydroxybenzenecarboxylic acid) into 100 cm3 conical Flask. Carefully add 7cm3 of ethanoic anhydride into the conical flask. Add 2 to 3 cm3 drops of Sulphuric acid. Swirl the contents of the flask thoroughly to ensure mixing and heat on a water bath at about 50 to 600C for about 15 to 20 minutes swirling occasionally.
Allow to cool and 75 cm3 of water, stir well and filter under reduced pressure.
- Purification of the crude oil.
Place the filtered solid into250 cm3 beaker and add 5cm3 of ethanol and 40cm3 of water. Heat gently until all aspirin has dissolved (NB: DO NOT BOIL THE SOLUTION)
Allow the solution to cool slowly. Needle-like crystals of aspirin will form. When a good crop of crystals have formed, cool thoroughly using an iced water bath and filter under reduced pressure. Wash the crystals with a little cold water, put it on filter paper, and place it on a watch glass and leave to dry. When completely dry, weigh accurately and record the mass of the pure aspirin. Aspirin decomposes below its melting temperature so that melting temperature cannot be used as a check on impurity.
Tabulated Experimental Data:
| Weight of 100 cm3(g) | 42.34g |
| Weight of Flask and Salicylic Acid (g) | 46.34g |
| Weight of Salicylic Acid (g) | 5.0g |
| Weight of Filter Paper (g) | 0.9888g |
| Weight of Watch glass (g) | 60.2501g |
| Weight of Filter Paper +Aspirin +Watch glass (g) | 62. 49g |
| Weight of Actual yield of aspirin (g) | 2.47g |
Calculations.
Theoretical Yield of AspirinFormula:
| Salicylic Acid | = | x grams Salicylic Acid started with | ||
| Aspirin | ? g aspirin | |||
Calculation for Theoretical Yield:
| 138g g/mol | = | 2.011g Salicylic Acid | = | 361.98g Salicylic Acid | = | 2.623g |
| 180g g/mol | ? g Aspirin | 138g Aspirin |
Actual YieldCalculations:
% yield = Actualyield x 100
Theoretical yield
So: 2.30g x100 = 88.02% 2.62g
Results and conclusion.
This experiment confirmed that aspirin can be produced by esterification and that I was able to determine a percentage of the yield. Ethanol anhydride (alcohol) reacts with salicylic acid (acid) to form the ester (aspirin), as crystals are formed and dried, measuring 2.28 g. As a result, a yield of 88.02% was obtained based on our theoretical yield. During the experiment, I was not able to the 2.623g of aspirin, which is a 100% yield. The possible reason why I was not able to arrive at 100% yield was because of the following reasons.
- Some not all crystals from the conical flask were extracted from the glass surface.
- Another reason is that maybe more ethanoic anhydride should have been used, which should have influenced the equilibrium to shift more to the forward, thus giving better yield.
Investigation of effects of Antibiotics on bacterial growth.
Antibiotics are chemical agents that can kill or interfere with the growth of bacteria. They are useful in making drugs to treat diseases related to bacteria.
Apparatus.
- Fresh ship or pig heart
- Wax dissection tray
- Scalpel
- Scissors
- Mounting needle
- Paper towel
- Disinfectant in a beaker for discarded dissection instruments.
Procedure.
- Prepare a dissection tray with bacteria extracted from the sheep or pig heart.
- Prepare the solutions used for the test
- Prepare four paper towels per from the dissection tray.
- When a jelly-like substance has formed (agar), turn the tray upside down. Partition the base to sections by making a cross drawing using a marker pen. Label the partition A, B, C, D
- Use the mounting needle to place the dried paper towel from each section. Place in disinfectant if the mounting needle maybe has been contaminated by coming into contact with the surface.
- Label the plate with your name and out a date then incubate the inverted lib for 2-3 days at 20-250
- Observe the plates without opening them.
Any measurements which will help in the investigations should be recorded.
.
Risk assessment.
| Hazard | Risk | Control measure |
| Bacteria can be pathogenic.
| When the bacteria is touched when the plate is open | Seal the tray to ensure it’s not open and ensure to wash hand regularly |
| The Bunsen burner and pair of forceps can cause burns. | Accidental skin burns when placing discs on the plate. | Anybody part should be kept away from the flames or hot forceps. |
| Handling scissors and scalpels can cause skin cuts. | Accidental cuts on the skin while performing dissections. | Keep all the sharp apparatus lock away and only remove them when in use. |
| Carrying apparatus and chemicals around the laboratory | Can cause severe burns in case of chemical spillage or the apparatus can fall and cause an injury | Wear full PPE’s Ensure a clear through way when carrying the chemicals or apparatus |
| Student behavior | Lack of compliance with laboratory rules and regulations can cause accidents. | Number of students in the lab should be kept very minimal. |
References.
Cannon, J., Nuckels, E., Khatmullin, R., and Lauer, A., 2016. Survey of Chemistry II.
Olmsted III, J.A., 1998. Synthesis of aspirin: A general chemistry experiment—Journal of chemical education, 75(10), p.1261.
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Pbiol.rsb.org.uk. 2020. Investigating Anti-Microbial Action. [online] Available at: <https://pbiol.rsb.org.uk/health-and-disease/hygiene/investigating-anti-microbial-action> [Accessed 14 May 2020].
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“The Mechanisms of a Substitution Reaction.” Chemtopics. N.p., 2012. Web. Oct.<http://www.chemtopics.com/aplab/mechanism.pdf> .
Haas, C.N., Rose, J.B., and Gerba, C.P., 1999. Quantitative microbial risk assessment. John Wiley & Sons.