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?