Question

Name atien: Post Lab Questions Data for calculating amount of iron in the tablet MEnhe diferene in read janly 1 run) initial buret reading (KMnO.) Final buret reading (KMnO) 37-5um10.4omL 55-85.lono Molar Mass of Fe Using the Average molarity in Part A and the balanced equation: MnO +5 Fe+ 8H- Mn+5 Fe" 4 H Calculate the milligrams of iron (Fe) in the iron pill with your titration data. Show all calculations below clearly and completely and include appropriate units SOl 10.40 mL 9104 L Ane Mye 01S48M-DILE Dct9052 Mot Mn Smat fe 0.000170831 Mn0.000 541 mal Mn =0-0532561419b 53.286 5321mg .0.000 954Imst 55.85a Imol Now, read the pill bottle's label to see how many mg of iron they claim to put in, and record it: Calculate the percent error for the Fe in the iron pill, using your calculated amount as "experimental", and the pill label amount as "theoretical", determind loh65-521 Pin S3 29 mfe in 3.2h Report Page 2 of 2

please use this information I provided to answer this...

I want to compare the answers.

Answer 1

Ans:

Initial burette reading: 0.00 mL

Final burette reading: 10.40 mL

Volume of KMnO4 added, V = (10.40-0) = 10.40 mL

Molarity of KMnO₄ solution, M = 0.018348 M

Number of moles of KMnO4 used, n = M x V = 0.018348 x 10.40 x 10^-3 = 1.908192 x 10^-4 mol.

Balanced redox reaction: MnO₄^- + 5 Fe²⁺ + 8H⁺ ---> Mn²⁺ + 5 Fe³⁺ + 4 H₂O

From the above equation it is clear that 5 moles of ‘Fe²⁺’ demands 1 mol of KMnO₄.

So, 1.908192 x 10^-4 mol of KMnO4 must have consumed (1.908192 x 10^-4 x 5) = 9.54096 x 10^-4 moles of ‘Fe²⁺’.

Molar mass of ‘Fe’ = 55.85 g/mol

Mass of 9.54096 x 10^-4 moles of ‘Fe²⁺’ = 9.54096 x 10^-4 x 55.85 = 0.053286 g = 53.286 mg

Mass if iron in pill determined by the experiment = 53.286 mg

mg of Iron claimed by the company in the pill = 65 mg

% error = {(65-53.286)/65} x 100 = 14.945 %

CONCLUSIONS: Mass of Iron present in the pill as determined by the experiment is less than it is claimed by the company.

Possible reasons for the error:

1. Titration is done only once which might have included lots of handling error. Significant repetition of the titrations until getting a constant value helps in reducing the error.
2. It is given that molarity of KMnO4 is taken from part ‘A’ which is experimental. There may be some error contributions from this section too which is adding on to the error in part ‘B’.

To reduce the error, care in handling (avoid spilling of reagents etc) and repetition to get average value helps

3. Care should be taken while dissolving the pill. Dissolution of all iron present in the pill must be complete.
4. Lastly, the claim itself may be wrong which is showing in the form of error.