Result Analysis Of Aspirin

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Aspirin is a widely name used to refer to a chemical compound known as acetylsalicylic acid. It is commonly used as a pain killer. Salicylic acid is extracted from the bark of willow plant. In the past, the bark willow plant was used as the remedies for tonics and headache. Currently, salicylic acid is administered to patients in aspirin form which is less irritating to the stomach as compared to salicylic acid. Aspirin is synthesised by reacting excess acetic anhydride with the salicylic acid. During its synthesis a small quantity of a strong acid is used as a catalyst. Strong phosphoric acid was used as a catalyst in this experiment. The excess acetic acid was quenched by addition of water. Beer’s law shows the relationship
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C7H6O3 (aq) + C4H6O3 (aq) –> C9H8O4(s) +C2H4O2 (aq)
Salicylic acid was the limiting reactant while acetic anhydride was an excessive reactant. One mole of salicylic acid reacted with one mole of acetic anhydride to yield one mole of acetylsalicylic acid and one mole of salicylic acid. The theoretical of yield is calculated from the reaction information as follows:
Obtain the mass of 5ml of acetic anhydride, density of acetic anhydride=1.08g/mol,
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2.001g/(138.118g/mol)=0.01449 moles
Theoretical yield of aspirin= (g=MM X mol) = (244.154g x 0.01449 moles) = 3.54g
The apparatus was set-up in fume hood. After adding 5ml of acetic anhydride and five drops of 85% phosphoric acid into 50ml Erlenmeyer flask which contained 2.001g salicylic acid, the flask was heated on a hot plate (75℃ ) for 15 minutes while stirring the flask’s content. A butcher funnel was then set-up for filtration of the flask’s content.
The purple solution was noted after mixing 0.5ml aspirin and 0.025ml Fe (NO3)3 in volumetric flask. Color change indicated the ions complexion point of the reaction.
Mass of synthesized aspirin is calculated by:
Mass of aspirin 0.5ml
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