The aim of the experiment is to determine the percentage of aspirin in different commercial preparations (Aspirin & Magnyl) and to find out which is the best value for money.

Essay by MantuCollege, UndergraduateA, January 2007

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Report: Analysis of Aspirin Tablets.

Aim: The aim of the experiment is to determine the percentage of aspirin in different commercial preparations (Aspirin & Magnyl) and to find out which is the best value for money.

Hypothesis: Aspirin is a monoprotic (monobasic) acid and therefore, reacts with sodium hydroxide solution according to the equation:

CH3-COO-C6H4-COOH + NaOH à CH3-COO-C6H4-COONa + H2O

:

*Aspirin and Magnyl tablets.

*NaOH

*Phenolphthalein

*95 % ethanol

*Digital scale

*Conical flask

*Graduated cylinder

*Beaker

*Clamp

*Magnate stirrer

*Funnel

*Pipette

*Burette

*Pestle & Mortar

Procedure:

*Aspirin 500mg, 20 tablets for 27.15 DKK. Each tablet for 1.35 DKK.

*Magnyl 500mg, 20 tablets for

1)Weigh out accurately one Aspirin or Magnyl tablet.

2)Grind the tablet and put it into a 50cm3 conical flask and dissolve it in 10cm3 of 95% ethanol.

3)Titrate this solution with 0.1 mol dm-3 sodium hydroxide solution.

4)Use two drops of phenolphthalein solution as indicator.

5)Keep titrating the solution until you get a change in colour. As you see a light purple in your solution, stop titrating and read the burette.

Setup:

1.I accurately weighed the mass of an Aspirin tablet on a digital scale.

m (Aspirin tablet, 500mg) = 0.60g

*500mg is the mass of active ingredients in a single aspirin tablet.

2.I grinded the tablet with a pestle and mortar. In order to get sure that there is no aspirin left inside the mortar after grinding, I poured some drops of ethanol and stirred well and poured it into the conical flask.

3.I measured 10cm3 of 95% ethanol in a burette. Then I poured the mentioned amount of ethanol into the conical flask and dissolved the grinded tablet with it.

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4. I attached a 50cm3 burette to a clamp and filled it with 0.1 mol dm-3 sodium hydroxide...