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Iron tablet colorimetry help

I'm carrying out a project in which I am to determine the concentration of an unknown iron solution using colorimetry. I'm confused with calculating the concentration of my unknown iron solution after preparing standards and creating a calibration curve. An iron tablet was dissolved in 20 ml of 1 mol l-1 sulfuric acid. This was transferred to a 250 ml volumetric flask, made up to the mark with deionised water, stoppered and inverted. I then pippetted 5 ml of this solution into another 250 ml volumetric flask and made up to the mark using deionised water. This was the solution I took an absorbance reading from.

So I have added the complex to make it coloured and I took an absorbance reading. After working out the unknown concentration from the curve would I times it by the dilution facor of 12.5 (250/20) AND a dilution factor of 50 (250/5)? Is that correct?
Original post by ahfae
I'm carrying out a project in which I am to determine the concentration of an unknown iron solution using colorimetry. I'm confused with calculating the concentration of my unknown iron solution after preparing standards and creating a calibration curve. An iron tablet was dissolved in 20 ml of 1 mol l-1 sulfuric acid. This was transferred to a 250 ml volumetric flask, made up to the mark with deionised water, stoppered and inverted. I then pippetted 5 ml of this solution into another 250 ml volumetric flask and made up to the mark using deionised water. This was the solution I took an absorbance reading from.

So I have added the complex to make it coloured and I took an absorbance reading. After working out the unknown concentration from the curve would I times it by the dilution facor of 12.5 (250/20) AND a dilution factor of 50 (250/5)? Is that correct?


Just follow the tablet.

1 tablet was made up to 250ml in the first volumetric flask. This solution has a concentration of 1 tablet/250ml

THEN a 50 fold dilution was made to read in the colorimeter.
Reply 2
Original post by charco
Just follow the tablet.

1 tablet was made up to 250ml in the first volumetric flask. This solution has a concentration of 1 tablet/250ml

THEN a 50 fold dilution was made to read in the colorimeter.


So would I times the concentration of the unknown by 50 to adjust for the dilution?
Original post by ahfae
So would I times the concentration of the unknown by 50 to adjust for the dilution?


yup

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