[teddybear_01]

hello
to investigate the percentage of purity of iron i iron tablets what else would i have to do apart from titration and colorimtery?

Also, how could i investigate effectiveness of sunscreen aginast UV?

Lastly, how could i briefly investigate the conc of caffeine in diff coffee brands?

I am desparate for help and would rly appreciate it asap!

Thanks

[Klaynos]

The first two I'd do using optical effects...

The first by doing some magnetrometry... And some clever maths, and the second by just doing a transmission spectrum through the sample using a lightsource + detector that can do UV.

But neither method are chemical methods so....

[John Cuthber]

I'd not bother with magnetometry. I'd dissolve the tablets in dilute acid, oxidise with H2O2 to get it all into Fe(III) then measure it colourimetrically. If I wanted to be classical about it I'd not oxidise the extract, I'd send it through a Jones reductor and then titrate the eluant with KMnO4
I have a feeling that you would need to do some sort of purification of the coffee extract before you could do a UV determination on the caffeine. I'd bet on chromatography.
Not sure about the sunscreen- some sort of absorbtivity measurement.