Objectives
:
To
determine the actual content of Ibuprofen in Ibuprofen tablet.
Material:
Ibuprofen powder, chloroform, ethanol (96%), phenolphthalein
solution, 0.1M sodium hydroxide
Apparatus:
filter paper, filter funnel, 100ml measuring
cylinder, 100ml burette, 100ml beaker, hair dryer, conical flask
Procedure
1.
20
Ibuprofen tablets were weighed and crushed into powder using pestle and mortar.
2.
A
quantity of powder was measured to contain exactly 0.5 g ibuprofen and then the
powder was extracted with 20 ml chloroform for 15 minutes. The mixture was
filtered by using filter paper.
3.
The
residue washed with 3 . 10 ml chloroform and gently evaporate the combined
filtrate just to dryness in a current of air. The residue was dissolved in 100
ml with ethanol (96%) previously neutralized to phenolphthalein solution.
4.
The
solution was titrated with 0.1M sodium hydroxide to end point with
phenolphthalein solution as the indicator. The content of ibuprofen was
calculated if each ml of 0.1M sodium hydroxide is equivalent to 0.02063 g of C13H18O2.
Result
Calculation for weight of tablet
powder containing 0.5 g of ibuprofen;
Weight
of powder of 20 tablet ibuprofen=7.840g
1 tablet= 200mg ibuprofen
20 tablet= 20×200mg = 4000mg
ibuprofen =4 g ibuprofen
7.840g tablet powder = 4 g ibuprofen
X g = 0.5 g ibuprofen
X = (0.5 ×7.840)/4 = 0.98 g of tablet powder
Thus,
0.98g of tablet powder was weighted and
dissolved with 20ml chloroform.
Calculate the content of
ibuprofen after titration;
Initial burette
reading of 0.1M NaOH
|
100 ml
|
End point burette
reading of 0.1M NaOH
|
79 ml
|
Volume of 0.1 M
NaOH use
|
=100-79
=21 ml
|
The content of
Ibuprofen in solution
|
NaOH +
C13H18O2 C13H17ONa + H2O
From equation, 1
mol of NaOH = 1 mol of C13H18O2
No. of mole of
NaOH = MV = (0.1)(0.021) = 2.1x10-3 mol
Hence, 2.1x10-3 mol of NaOH = 2.1x10-3 mol of C13H18O2
If each ml of
NaOH is equivalent to 0.02063g of C13H18O2
21.0 ml x 0.02063
= 0.43323g of Ibuprofen
Therefore, The
content of Ibuprofen is 0.43323g.
|
Calculation for
assay (standard deviation)
|
=(( Experimental value - Theoretical value )/(Theoretical value)) x 100%
= ((0.43323-0.5 )/0.5) x 100 %
= - 13.35%
This means the experimental
value is lower than the theoretical value by 13.35%.
|
In the theory, the amount of
ibuprofen is 0.5g. Meanwhile in experiment, after calculation the amount of
ibuprofen in the solution is 0.43323g. There is a small differences compare to
the theoretical value with percentage of deviation is 13.35%. the resulted
deviation may be due to a certain errors when we are conducting the experiment.
One of the possible errors detected
may due to the ibuprofen that we used for the experiment has expired, causing
the loss of active ingredients in the tablets as the active ingredients might
have decompose. Therefore, to increase the accuracy of the experiment, we
should use ibuprofen tablets that are not expired.
Others possible errors are, the
active ingredient might be left behind a little because we may not rinse it
correctly. Besides, the solution are not filtered through a sintered glass
crucible but using filter paper and filter funnel. This will cause some of the
powder that are not dissolved in the chloroform will pass through into the
conical flask. Lastly, the error might happen due to the titration of the
solution with sodium hydroxide. Lastly we might miss the actual end-point of
the solution that turn the solution from colourless to pale pink in colour.
Conclusion
The
content of Ibuprofen is 0.43323g which differ from the theoretical value by
13.35% due to many factors.
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