# Estimating the Iron(II) content in an iron tablet using a standard solution of potassium manganate (VII)

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Introduction

Estimating the Iron(II) content in an iron tablet using a standard solution of potassium manganate (VII) Results Table 1: Data collection - burette reading before and after potassium manganate is used to reach the end-point/ml�0.05 Trial Test 1 Test 2 Initial Reading 0 19.15 16.5 Final Reading 19 38.25 35.6 Table 2: Processed data - volume of potassium manganate used to reach end point (Volume = final reading - initial reading) Trial Test 1 Test 2 Volume used /ml�0.1 0 19.1 19.1 Calculating the amount of iron(II) present The iron was oxidized from its 2+ state to 3+ by sulfuric acid: And the manganate iron was reduced as follows: This half equation is balanced as follows: Since the above equation involves the transfer of five electrons, the equation involving iron needs to be multiplied by five before the two half equations can be added together: Adding the two half equations: This simplifies to: This equation shows that for every five present, one is required for the reaction to be completed. ...read more.

Middle

solution used = 25ml�0.05 Percentage uncertainty for burette reading = ==> Volume of potassium manganate used = 19.1ml�0.05 Adding the percentage uncertainties together, the overall uncertainty is 0.462%. Converting this to the uncertainty of the total amount of iron sulfate present, we obtain: Thus, the total amount of iron sulfate can be said to be 145mg�0.670 Literature value for mass of Iron Sulfate present in one tablet is 160mg. The percentage error of the experimental results can thus be calculated as follows: Converting this into absolute error in the amount of iron, we obtain: Thus, the total amount of iron sulfate with respect to its error value can be said to be 145mg�13.6. Conclusion In this investigation it was found through calculations that each of the iron tablet contained approximately 145mg of Iron (II) Sulfate. This is 15mg less than the listed amount of 160mg on the package, or 10% less than the literature value. ...read more.

Conclusion

The result is that the volume of manganate (VII) solution used might have been bigger than necessary due to decreased concentration as a result of decomposition. To minimize this from happening, the solution should be kept in a clean container and exposed to as little light as possible, as the solution decomposes faster under light and contaminated container. The obtained result was smaller than literature value, and this may have been because some of the powdered tablet was left in the mortar. To improve the accuracy of this experiment, one should wash the mortar with sulfuric acid or distilled water, which can then be transferred to the volumetric flask. This would allow more of the iron tablet to be contained in the acidic solution, thus increasing the amount of iron present. To extend this investigation, one can experiment on more types of iron tablets. Alternatively, a different content such as calcium or potassium can be investigated. This would require different types of tablets to be used. ?? ?? ?? ?? Candidate Name: Yi-Chun Teng Candidate Number: 001407-038 1 ...read more.

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