Hi guys,

Hi was looking to get some help with an experiment. Currently I trying to determine the amount iron in cereal and was hoping to get some help with one of the questions I have been given.

First off I am given the recorded absorbance across the region 470 – 490 nm for the 3.00 mg L–1 iron(III) standard solution constructed in Part 1 above yielded a λmax of 478 nm with an absorbance of 0.674 AU on an instrument with a 1 cm path length.

I have calculated the molar absorptivity to be e= 0.225 L mg^-1 cm^-1 from e = A/bc (a variant of Beer's Law).

I then have been given a set of values for %transmittance of 80, 60, 50, 40, 30, and 20. I have calculated their A values using A = -log (%T/100).

However they want me to find:

(1) the amount of [Fe3+] required (mg L–1);

(2) the quantity Fe3+ required in 50 mL (mg); and

(3) Volume Fe3+ standard solution required (mL)

For (1) I am guessing that I need to use A = ebc and solve for c? (2) I am lost on and same with (3). Namely because of what they say at the bottom 3rd of the calculation page. If I already have A=ebc where I know A, e, b, and then they give us c what exactly I am using to find (2) and (3) for each solution?

- This is the background information of the experiment.

- This the calculation page we are given.

- This the question exactly. It refers to using the A value I calculated above.