How much iron is in an iron tablet?

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How much iron is in an iron tablet?

• Group members Choi Chuen Ching (5)
• Fong Ka Yee (6)
• Leung Chi Lai (12)
• Lui Lai Sin (16)

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Aim

• To investigate how much iron is in iron
  tablets.
• 2. To compare the percentage of iron in iron
  tablets from two different manufacturer.
• 3. To find out which one is worth buying.

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Why iron is essential to our body?
Because iron is necessary for the formation of
haemoglobin. The deficiency of iron may lead to a
disease called anaemia, people who suffer this
disease may need to take iron tablet under the
guidance of doctor. We can obtain iron from the
following food sources Liver, eggs, beef, green
leafy vegetables, etc. Daily requirement of
iron For male is 10mg and for female is 18mg.
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Principles A. Standardization of Potassium
Permanganate Solution Potassium permanganate
slowly decomposes in solution, especially in
sunlight and readily oxidizes organic matter. It
has to be stored in brown bottle and has to be
standardized before use. The most common
reagents which are used for the standardization
of KMnO4 are oxalic acid, sodium oxalates,
ammonium iron(II) sulphate or arenious oxide.
KMnO4 is deep purple in color and is reduced to
almost colorless solution (Mn2 salts are light
pink in color). It does not require a chemical
indicator for the detection of end point.
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In this experiment, ammonium iron(II) sulphate is
used as a primary standard to standardize the
KMnO4 solution. Solid ammonium iron (II)
sulphate(AIS) is stable at room temperature and
can be obtained in pure state. It can be used as
a primary standard in redox titration. A neutral
solution of AIS is unstable and iron will
precipitate out as the hydroxide. Therefore it
should be dissolved in an acidified solution,
preferably oxygen free. In this experiment, a
standard ammonium iron(II) sulphate solution is
used to standardize the potassium permanganate
solution. The overall equation for the reaction
is MnO4- 5Fe2 8H Mn2 5Fe3 4H2O
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B. Determination of the mass of iron in one gram
of the iron tablet The iron in iron tablets
comes from hydrated iron(II) sulphate (sometimes
called hydrated ferrous sulphate). FeSO4.7H2O. As
its name suggests, iron(II) sulphate contains
Fe2 ions. These react with the MnO4- ions in the
potassium permanganate as shown in the equation
below 5Fe2 MnO4 8H 5Fe3 Mn2
4H2O The colour of the potassium permanganate
disappears as it reacts with the Fe2 ions. This
provides a way of deciding when the titration is
complete because, when all the Fe2 ions are
gone, just one drop extra of potassium
permanganate solution will make the titration
mixture turn pale purple.
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Procedures

• A. Standardization of potassium manganate(VII)
  solution
• About 9.8G of ammonium iron(II) sulphate was
  accurately weighed out. Then it was dissolved in
  25ml of sulphuric acid. The mixture was diluted
  with distilled water and was made up to exactly
  250.0ml of solution.
• 25.0ml of this solution was pipetted into a
  conical flask. 25ml of 1M sulphuric acid was
  added to it.
• It was titrated with potassium manganate(VII)
  solution until a permanent pink colour was
  obtained (would not disappear after 30 seconds).
• The molaruty of the manganate(VII) solution was
  calculated.

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B. Determination of the mass of iron in one gram
of the iron tablet 1)  Five iron tablets were
weighed accurately and their masses were
recorded. . 2)  They were grinded up in
a mortar and were pestled with about 5 cm3 of 1M
sulphuric acid.
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3)  The acid and tablets were transferred through
a small filter funnel into a 250.0 cm3 volumetric
flask. The mortar and pestle were rinsed with
further quantities of acid, each portion were
transferred carefully into the flask, until all
trace of the iron tablets had gone.
4)  The funnel was rinsed with more acid, and
then 1M sulphuric acid was added to the flask
until the solution reaches the 250.0 cm3 mark.
The flask was stoppered and was inverted several
times to mix the solution.
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5)   25.0 cm3 of the solution was pipetted from
the volumetric flask and was transferred to a
conical flask. 6)   A burette was filled with the
potassium manganate(VII) solution. 7)   The
potassium manganate(VII) solution was titrated
against the solution in the conical flask. The
volume of potassium manganate(VII) solution used
at the end point was recorded. 8)   The above
steps were repeated but using different brands of
iron tablets in step (1).
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Result
Standardization of potassium permanganate
solution
Trial 1 2 3
Initial/ml 0.10 0.10 0.20 0.00
Final/ml 24.90 25.00 25.00 24.70
Vol. Used/ml 24.80 24.90 24.80 24.70
Average volume used 24.80ml
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Enteric-coated 167mg iron tablets
Weight of 5 tablets 1.067g
Trial 1 2 3
Initial/ml 0.00 3.00 5.70 8.40
Final/ml 3.00 5.70 8.40 11.20
Vol. Used/ml 3.00 2.70 2.70 2.80
Average volume used 2.73ml
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Enteric-coated 300mg iron tablets
Weight of 5 tablets 1.580g
Trial 1 2 3
Initial/ml 0.95 6.45 17.50 22.85
Final/ml 6.45 11.85 22.85 28.25
Vol. Used/ml 5.50 5.40 5.45 5.40
Average volume used 5.42ml
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After calculation, we found that there is
142.76mg of iron present in the 167mg tablet
and 191.42mg of iron present in the 300mg
tablet. Then we decided to remove the coating
of the tablet and see whether the coating will
affect the iron content.
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How about the iron tablets without
enteric-coating?
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167mg iron tablets after removing the
enteric-coat
Weight of 5 tablets 0.959g
Trial 1 2 3
Initial/ml 0.00 2.55 4.90 7.25
Final/ml 2.55 4.90 7.25 9.65
Vol. Used/ml 2.55 2.35 2.35 2.40
Average volume used 2.37ml
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300mg iron tablets after removing the
enteric-coat
Weight of 5 tablets 1.312g
Trial 1 2 3
Initial/ml 36.20 40.70 45.00 39.10
Final/ml 40.60 45.00 49.30 43.40
Vol. Used/ml 4.40 4.30 4.30 4.30
Average volume used 4.30ml
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After calculation, we found that there is
138.48mg of iron present in the 167mg tablet
and 182.88mg of iron present in the 300mg
tablet.
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Discussion
Manufacturer of the iron tablets 167mg tablet
--- Christo Pharmaceutical LTD HK 300mg tablet
--- Apotec Inc.
The table showing the mass of iron present in an
iron tablet
Manufacturer Mass Christo 167mg tablet Apotec 300mg tablet
Tablets with enteric-coating 142.76mg 191.42mg
Tablets without enteric-coating 138.48mg 182.88mg
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It is found that the difference between the
experimental value and the described value of the
Christo is smaller than that of Apotec.
The table showing the of iron present in an
iron tablet
Manufacturer of iron Christo 167mg tablet Apotec 300mg tablet
Tablets with enteric-coating 14.3 19.1
Tablets without enteric-coating 13.9 18.3
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Source of error The iron tablets are not
completely dissolved in sulphuric acid. The
percentage of iron in enteric-coating may not be
the same as that of the inner part of the
tablets. Potassium permanganate may decompose so
that the volume of KMnO4 added may not accurate
enough. The colour of the coating may affect the
observation of end point during titration.
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Observations We found that the 300mg tablet is
more difficult to dissolved in sulphuric
acid. Improvement Potassium permanganate
solution should be used immediately after pouring
out of the brown bottle.
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Conclusion
We found that the difference between the
experimental value and the described value of
167mg tablet was smaller than that of 300mg
tablet. Therefore the manufacturer of 167mg
tablet (i.e.Christo Pharmaceutical LTD HK)is
more reliable than that of 300mg tablet (i.e.
Apotec Inc.). On the other hand, the price of
both kinds of tablets were the same. So 300mg
tablet is more worth buying than 167mg tablet.
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The End