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.

Only available on StudyMode
  • Download(s): 117
  • Published: January 27, 2007
Read full document
Text Preview
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.

.

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 stirrer. Later on I poured two drops of phenolphthalein with a pipette as an indicator.

6.I started the titration. I stopped the titration as a light purple colour appeared in the solution and wrote down the data.

7.I repeated the procedure for 5 times to get a reliable result.

8.I washed the materials at the end of each experiment and then dried them.

Data Collection:

I have written my collected data in the table below.

m (Aspirin tablet) = 0.60g

m (Aspirin, active ingredients) = 500mg 0.500g

Price (Aspirin 500mg, 20 tablets) = 27.15 DKK

Each tablet costs = 1.35 DKK

Aspirin®

Trial #Initial volume of BuretteFinal volume of Burette

1.0.00 cm327.8 cm3

2.0.00 cm327.5 cm3

3.0.00 cm327.6 cm3

4.0.00 cm327.5 cm¬¬¬3¬¬¬¬¬¬¬

5.0.00 cm327.3 cm¬3

m (Magnyl tablet) = 0.74g

m (Magnyl, active ingredients) = 500mg 0.500g

Price (Magnyl 500mg, 100 tablets) = 40.10 DKK

Each tablet costs = 0.401 DKK

Magnyl

Trial #Initial volume of BuretteFinal volume of Burette

1.0.00 cm323.9 cm3

2.0.00 cm323.5 cm3

3.0.00 cm323.4 cm3

4.0.00 cm324.1 cm3

5.0.00 cm323.6 cm3

Data Processing:

Aspirin®

Average (Final volume of Burette) = (27.8 cm3 + 27.5 cm3 + 27.6 cm3 + 27.5 cm3 + 27.3 cm3)

5

= 27.5 cm3

1000

= 0.0275 dm3

1)n (OH-) = 0.01 M 0.0275 dm3 *the unit of concentration can be the written

= 0.01 dm3 0.0275 dm3 both as a capital M or dm3.

= 0.00275 mole

2)n (acetylsalicylic) = n (OH-) due to the mole ratio between them.

The mole ration between (acetylsalicylic) and (OH-) is 1:1¬

Finding molecular mass of (acetylsalicylic)

3)m (acetylsalicylic) = mole molar mass (acetylsalicylic) C (9) = 108

= 0.00275 180 g mol H (8) = 8

= 0.495g x 1000 O (4) = 64

= 495 mg =180 g mol

4)Uncertainty:

500 mg - 495 mg x 100 = 1%

500 mg

5)Mass percentage of Aspirin® =

0.495 g x 100 = 82.5%

0.6 g

6)Uncertainty errors (Apparatus) :

Accuracy x 100 =

Volume

*Conical flask...
tracking img