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.
*95 % ethanol
*Pestle & Mortar
*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.
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.
4.I attached a 50cm3 burette to a clamp and filled it with 0.1 mol dm-3 sodium hydroxide solution through a funnel.
5.I put the magnate inside the conical flask and placed the flask on the magnate...