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How might you investigate how quickly Fe2+ is released from an iron tablet?

Just that really. I'm guessing you would need hydrochloric acid and 37 degress to mimic stomach conditions, but I'm abit cofused as to how you would continually measure it - maybe something to do with a colorimeter?
Thank you!
Original post by Emmmaaaa...
Just that really. I'm guessing you would need hydrochloric acid and 37 degress to mimic stomach conditions, but I'm abit cofused as to how you would continually measure it - maybe something to do with a colorimeter?
Thank you!


Maybe you could add a little hydrogen peroxide and ammonium thiocyanate to the solution.
The iron(II) will dissolve and get oxidised to iron(III) which will then form a complex with the thiocyanate ions and give a deep red colour. You could then monitor the colour intensity using a colourimeter.
Original post by charco
Maybe you could add a little hydrogen peroxide and ammonium thiocyanate to the solution.
The iron(II) will dissolve and get oxidised to iron(III) which will then form a complex with the thiocyanate ions and give a deep red colour. You could then monitor the colour intensity using a colourimeter.

Okay, thank you!
Original post by Emmmaaaa...
Just that really. I'm guessing you would need hydrochloric acid and 37 degress to mimic stomach conditions, but I'm abit cofused as to how you would continually measure it - maybe something to do with a colorimeter?
Thank you!

Colorimetry is arguably the best method.

As charco suggests, adding a suitable oxidising agent and ligand to form a distinctly coloured complex would work.

Alternatively, you could use a titrimetric method in which you prepare multiple solutions of equal volume with the same number of iron tablets all kept at the same temperature, leaving them for different, known lengths of time and titrate them against acidified K2Cr2O7 (since you have stated you are using HCl, you cannot use KMnO4). A titre-time graph could then be plotted and using tangents, you can estimate the rate at which Fe^2+ is released at any given time.

However, this method would need to be repeated several times and would likely require the iron tablet solutions to be prepared under an inert atmosphere to minimise the extent to which the dissolved Fe^2+ oxidises. This may make it difficult to attempt.

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