SSCE VCE Chemistry Quantifying Atoms and Compounds: The amount of iron in a newly de

Question

The amount of iron in a newly developed, heat-resistant aluminium alloy is to be determined.
An 80.50 g sample of alloy is dissolved in concentrated hydrochloric acid and the iron atoms are converted to Fe²⁺(aq) ions.

This solution is accurately transferred to a 250.0 mL volumetric flask and made up to the mark.
20.00 mL aliquots of this solution are then titrated against a standard 0.400 M potassium permanganate solution.

Four titrations were carried out and the volumes of potassium permanganate solution used were recorded in the table below.

| Titration number | I     | II    | III   | IV    |
|------------------|-------|-------|-------|-------|
| Volume of KMnO₄ (mL) | 22.03 | 20.25 | 21.97 | 21.99 |

a. Write a balanced half-equation, including states, for the conversion of MnO₄⁻ ions, in an acidic solution, to Mn²⁺ ions.

b. Calculate the average volume, in mL, of the concordant titres of the potassium permanganate solution.

The amount of iron in a newly developed, heat-resistant aluminium alloy is to be determined - VCE - SSCE Chemistry - Question 1 - 2010 - Paper 1

Worked Solution & Example Answer:The amount of iron in a newly developed, heat-resistant aluminium alloy is to be determined - VCE - SSCE Chemistry - Question 1 - 2010 - Paper 1

a. Write a balanced half-equation, including states, for the conversion of MnO₄⁻ ions, in an acidic solution, to Mn²⁺ ions.

b. Calculate the average volume, in mL, of the concordant titres of the potassium permanganate solution.

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