Gravimetric Determination of Iron as Fe2O3

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Gravimetric Determination of Iron as Fe2O3

• Experiment 3

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Purpose

• To determine the amount of Iron (III) in a sample
  of unknown using the gravimetric analysis method.

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Gravimetric Analysis?

• Any analytical method that relies on measuring
  the mass of a substance to complete the analysis.

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How to obtain the product?

• Precipitation
• Treating the analyte with a suitable counter ion
  (base).
• Dehydration/Ignition
• Heated to dryness
• To achieve a reproducible, stable composition.
• To change the chemical form of the precipitant.

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Precipitation

• Measures taken to reduce super saturation and
  form easily filtered particles (precipitate)
• High temperature during precipitation.
• Slowly adding and vigorously mixing the reagents.
• Maintaining a large sample volume.
• Using homogenous precipitation.

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Reaction!

• Formation of precipitate
• Fe3 (2 x)H2O (base)? FeOOH.xH2O(s) 3H
• FeOOH.xH2O(s) (heat)? Fe2O3(s)

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Question?

• Why is the analyte treated with a counter ion?

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Answer

• To promote precipitation.