The purity of iron wire
What is the percentage iron content in iron wire?
Aim: To determine the percentage mass of iron in iron wire using volumetric
analysis.
Method:
1
Accurately weigh out approximately 1 g of iron wire.
2
Dissolve the iron wire in 3 M sulfuric acid and then make the solution up to
250 mL using distilled water.
3
Pipette 25 mL aliquots of the iron solution into four conical flasks.
4
Add approximately 10 mL of 1 M sulfuric acid to each of the four flasks.
5
Titrate the iron solution with standardised 0.02 M potassium permanganate
(KMnO4) standard solution
Results:
Iron solution
Mass of iron wire
Volume of solution
Iron aliquot
Volume of aliquot
Standard solution (0.02 M)
Rough volume
Volume 1
Volume 2
Volume 3
Average volume
Equation for the reaction and mole ratio
1
© NSW DET 2007
Calculations:
Step 1: Calculate the number of moles of MnO4- required to reach the endpoint.
Step 2: Determine the number of moles of Fe2+ in each 25 mL aliquot.
Step 3: Calculate the number of moles of Fe2+ in the 250 mL iron solution and hence
in the iron wire.
Step 4: Calculate the mass of iron in the iron wire and hence the percentage mass of
iron in the wire.
2
© NSW DET 2007