Redox and redox equilibria
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We carried out a redox titration experiment to determine the percentage of iron in a sample of ammonium iron(II) sulphate. When we were dissolving the ammonium iron(II) sulphate crystals in sulphuric acid (approx 1 mol/dm3) we were told not to heat it to assist dissolving. Why was this?
Igloo replies
Heating would encourage the oxidation of iron(II) ions to iron(III) ions by oxygen in the air. This would mean that fewer iron(II) ions would remain when the subsequent titration with manganate(VII) ions is carried out. This would result in an underestimation of the iron present in the crystals.
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Risk assessment
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updated: 12 March 2007
