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

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....

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.