How much iron is in an iron tablet

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)

Aim 1. 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.

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 10 mg and for female is 18 mg.

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 KMn. O 4 are oxalic acid, sodium oxalates, ammonium iron(II) sulphate or arenious oxide. KMn. O 4 is deep purple in color and is reduced to almost colorless solution (Mn 2+ salts are light pink in color). It does not require a chemical indicator for the detection of end point.

In this experiment, ammonium iron(II) sulphate is used as a primary standard to standardize the KMn. O 4 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: Mn. O 4 + 5 Fe 2+ + 8 H+ Mn 2 + 5 Fe 3+ + 4 H 2 O

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). Fe. SO 4．7 H 2 O. As its name suggests, iron(II) sulphate contains Fe 2+ ions. These react with the Mn. O 4 ions in the potassium permanganate as shown in the equation below: 5 Fe 2+ + Mn. O 4 + 8 H+ 5 Fe 3+ + Mn 2+ + 4 H 2 O The colour of the potassium permanganate disappears as it reacts with the Fe 2+ ions. This provides a way of deciding when the titration is complete because, when all the Fe 2+ ions are gone, just one drop extra of potassium permanganate solution will make the titration mixture turn pale purple.

Procedures A. Standardization of potassium manganate(VII) solution 1) About 9. 8 G of ammonium iron(II) sulphate was accurately weighed out. Then it was dissolved in 25 ml of sulphuric acid. The mixture was diluted with distilled water and was made up to exactly 250. 0 ml of solution. 2) 25. 0 ml of this solution was pipetted into a conical flask. 25 ml of 1 M sulphuric acid was added to it. 3) It was titrated with potassium manganate(VII) solution until a permanent pink colour was obtained (would not disappear after 30 seconds). 4) The molaruty of the manganate(VII) solution was calculated.

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 cm 3 of 1 M sulphuric acid.

3) The acid and tablets were transferred through a small filter funnel into a 250. 0 cm 3 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 1 M sulphuric acid was added to the flask until the solution reaches the 250. 0 cm 3 mark. The flask was stoppered and was inverted several times to mix the solution.

5) 25. 0 cm 3 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).

Result Standardization of potassium permanganate solution Trial 1 2 3 Initial/ml 0. 10 0. 20 0. 00 Final/ml 24. 90 25. 00 24. 70 Vol. Used/ml 24. 80 24. 90 24. 80 24. 70 Average volume used = 24. 80 ml

Enteric coated 167 mg iron tablets Weight of 5 tablets = 1. 067 g 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. 80 Average volume used = 2. 73 ml

Enteric coated 300 mg iron tablets Weight of 5 tablets = 1. 580 g 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. 45 5. 40 Average volume used = 5. 42 ml

After calculation, we found that there is 142. 76 mg of iron present in the “ 167 mg tablet” and 191. 42 mg of iron present in the “ 300 mg tablet”. Then we decided to remove the coating of the tablet and see whether the coating will affect the iron content.

How about the iron tablets without enteric coating?

167 mg iron tablets after removing the enteric coat Weight of 5 tablets = 0. 959 g 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. 40 Average volume used = 2. 37 ml

300 mg iron tablets after removing the enteric coat Weight of 5 tablets = 1. 312 g 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 Average volume used = 4. 30 ml

After calculation, we found that there is 138. 48 mg of iron present in the “ 167 mg tablet” and 182. 88 mg of iron present in the “ 300 mg tablet”.

Discussion Manufacturer of the iron tablets: “ 167 mg tablet” Christo Pharmaceutical LTD HK “ 300 mg tablet” Apotec Inc. The table showing the mass of iron present in an iron tablet Manufacturer Mass Tablets with enteric coating Tablets without enteric coating Christo Apotec “ 167 mg tablet” “ 300 mg tablet” 142. 76 mg 191. 42 mg 138. 48 mg 182. 88 mg

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 Tablets with enteric coating Tablets without enteric coating Christo Apotec “ 167 mg tablet” “ 300 mg tablet” 14. 3% 19. 1% 13. 9% 18. 3%

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 KMn. O 4 added may not accurate enough. ~The colour of the coating may affect the observation of end point during titration.

Observations: We found that the “ 300 mg tablet” is more difficult to dissolved in sulphuric acid. Improvement: ~Potassium permanganate solution should be used immediately after pouring out of the brown bottle.

Conclusion We found that the difference between the experimental value and the described value of “ 167 mg tablet” was smaller than that of “ 300 mg tablet”. Therefore the manufacturer of “ 167 mg tablet” (i. e. Christo Pharmaceutical LTD HK)is more reliable than that of “ 300 mg tablet” (i. e. Apotec Inc. ). On the other hand, the price of both kinds of tablets were the same. So “ 300 mg tablet” is more worth buying than “ 167 mg tablet”.

The End