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steven10137

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## Homework Statement

A sample of iron ore consisting of a mixture of FeO and Fe2O3 was dissolved in dilute sulfuric acid. The resultant solution was divided into two equal aliquots. The first aliquot was titrated with a potassium permanganate solution containing 6.30g of KMnO4 per litre, and required 15.0mL for complete reaction. The second aliquot was reduced with zinc and the solution then titrated with the potassium permanganate solution. 25.1mL was required for the second oxidation. Calculate the mass of each iron oxide in the original sample.

## Homework Equations

n=m/M, n=cV

## The Attempt at a Solution

1st aliquot:

Iron ore titrated with KMnO4

V(KMnO4) = 0.015 L

c(KMnO4) = 6.3 g/L

therefore: n(KMnO4) = cV = 6.3 x 0.015 = 0.0945 mol

2nd Aliquot:

Iron ore reduced with zinc and then titrated with same KMnO4

V(KMnO4) = 0.0251 L

c(KMnO4) = 6.3 g/L

therefore: n(KMnO4) = cV = 6.3 x 0.0251 = 0.15813 mol

I am totally confused and have no idea how to relate these values back in terms of the iron ore sample and how to even approach solving the problem.

Any Help would be greatly appreciated

Steven

by the way, this is an assignment out of my workbook and the answers (with no solutions) are:

m(FeO)=0.429 g

m(Fe2O3)=0.321 g