CERTIFICATE
This is to certify that Siddhant Sethi of class XII “D” has worked under my supervision on the project “THE ASSAY OF ASPIRIN” in chemistry
laboratory and completed it to my total satisfaction.
Date:
(Mr. R Choudhary)
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ACKNOWLEDGEMENT
It gives me immense pleasure to express my deep sense of gratitude towards my eminent chemistry teacher Mr. Rajeev Chaudhary who has always been there as guiding spirit behind the successful completion of the project.
I am also grateful to our Lab Assistant Mr. MP Singh for his valuable guidance and encouragement throughout the course and preparation of this project.
(Siddhant Sethi)
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INDEX S.No. TOPIC AIM 1.)
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2.)
INTRODUCTION
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3.)
INDUSTRIAL SYNTHESIS
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4.)
TITRATION
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5.)
REQUIREMENTS
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6.)
PROCEDURE
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7.)
OBSERVATIONS
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8.)
CONCLUSION
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9.)
PHOTO GALLERY
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BIBLIOGRAPHY
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10.)
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AIM
IN THIS EXPERIMENT OUR AIM IS TO RUN A TITRATION TO DETERMINE THE AMOUNT OF ASPIRIN (ACETYL SALICYLIC ACID) PRESENT IN AN ASPIRIN TABLET.
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INTRODUCTION
Aspirin is a salicylate drug, often used as analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an antiinflammatory medication. Sustained Release dosage form also acts as a blood thinner and is indicated in cardiac patients. The aspirin will be titrated against a standard solution of base, 0.100 M NaOH. Base will be dispensed from a burette into a beaker containing the dissolved (in ethanol) acid and phenolphthalein indicator, which will show a faint pink color in basic solutions. In addition to containing acetylsalicylic acid, any aspirin tablet also contains pharmaceutical aids like binding agent, disintegrating agent, polishing agent and other excipients as required.
MEDICAL USE: Aspirin is used to reduce fever and relieve mild to moderate pain from conditions such as muscle aches, toothaches, common cold, and headaches. It may also be used to reduce pain and swelling in conditions such as arthritis. Aspirin is known as a salicylate and a nonsteroidal anti-inflammatory drug (NSAID). It works by blocking a c ertain natural substance in your body to reduce pain and swelling.
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ASPIRIN SYNTHESIS AT INDUSTRIAL LEVEL: Synthesis of aspirin in industry is done in two steps. The first step in the industrial synthesis of aspirin is the Kolbe-Schmitt carboxylation reaction, in which sodium phenoxide adds to carbon dioxide
gas under pressure. This reaction yields an intermediate keto acid anion, which enolizes to produce salicylic acid.
The next step of the synthesis is the acetylation of salicylic acid with acetic anhydride, which occurs via a nucleophilic acyl substitution mechanism.
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This produces acetylsalicylic acid (M r= 180.2 gmol ), a white crystalline powder which is slightly soluble in water. The temperature is maintained at o
70-80 C.
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Once the aspirin is prepared it must be isolated from the reaction solution and purified. The aspirin is insoluble in cold water, and can be isolated by filtering the chilled reaction solution. Purification is necessary to remove any unreacted salicylic acid and acetic anhydride, as well as the acetic acid product and phosphoric acid. Acetic anhydride is caused to decompose by the addition of water once the formation of aspirin is complete:
The acetic acid and phosphoric acid are water soluble and can be removed by washing the aspirin with chilled water. Salicylic acid is only slightly soluble in water and is not completely removed in the washing step. Final purification is accomplished by the process of recrystallization. The impure aspirin is dissolved in warm ethanol. The solution is then cooled slowly, and the aspirin crystallizes out of solution leaving the salicylic acid and other impurities behind.
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TITRATION Aspirin is an acid. The active ingredient is acetyl salicylic acid. Different strengths of aspirin are based on the amount of active ingredients that they contain. Titration is a way to determine how much acid is in a solution by adding just enough base of a known concentration to +
neutralize the acid. In neutralization, the numbers of moles of acid, H , -
are combined with an equal number of moles of base, OH . In the titration we will be performing, we will dispense base into a known amount of acid solution to find the unknown concentration. If we wanted to know the concentration of an unknown base, we could titrate the base with an acid in the same manner.
CHEMISTRY OF THE TEST: The following reaction occurs.
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REQUIREMENTS Chemicals and Materials: 1. 0.100 M NaOH 2. Ethyl alcohol 3. Aspirin 4. Phenolphthalein indicator
Apparatus: 1. Burette 2. Mortar and pestle 3. 150 mL flask 4. Pipette
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PROCEDURE 1. Find the mass of an aspirin tablet. Grind each tablet into a fine powder by using a mortar and pestle. 2. Tare a piece of weighing paper on the balance. Carefully transfer as much powdered sample to a piece of paper and then determine the mass. 3. Place the powdered sample in a 150mL beaker. 4. Add a 10.0 mL portion of ethyl alcohol to the beaker and stir. 5. Add 25.0mL of water to the beaker. 6. Put 3 drops of the phenolphthalein indicator in your flask. 7. The burette is filled with 0.100M NaOH. Make sure there are no bubbles apparent in the burette. Record the initial volume on the burette. 8. Begin titrating, Add the NaOH in 1.0mL increments, making note of when the color change occurs. Continue adding base 5.0 mL past the equivalence point (the equivalence is approximately when the solution turned pink from the phenolphthalein). 9. Repeat steps 1-8 for the remaining tablets.
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OBSERVATIONS Volume of Aspirin Used Volume of NaOH Used (mL)(V1)
35 35 35
(mL)(V2)
11.4 11.5 11.5 Concordant Reading: 11.5 mL
MAspirin=? MNaOH=0.1 M VAspirin=35 mL VNaOH=11.5mL MAspirin × VAspirin = MNaOH × VNaOH MAspirin ×35=0.1×11.5 MAspirin =0.0328 M mAspirin=207 mg/ tablet
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CONCLUSION According to the experiment, the amount of aspirin present in each tablet of Disprin is 207 mg. The real amount may be of equal value if there weren’t any minor experimental errors which include :
Use of Laboratory reagents which are not as accurate as quality control reagents actually used for conducting QA studies.
The excipients add to the bulk of the tablet along with aspirin which may also interfere with the results.
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PHOTO GALLERY
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BIBLIOGRAPHY 1.
www.google.co.in
2.
NCERT(Class XII)
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