Question

I did a lab on the colorimetric determination of iron concentration and I'm not sure how to convert fe conc into ppm. For example, how would i convert 0.6 ug/ml to ppm?

Answer 1

ppm is a weight/weight ratio problem. That is, weight of solute/weight of solution... I am assuming the 0.60ug is in water having a density of 1g/ml. (Sounds like you are running the FeSCN+2 Kc experiment). Anyways, given 0.60ug/ml = 0.6ug solute/1.0g solution = 6 x 10^-7g solute/1.0g Solution. By converting dimensions to same units one gets the ratio as the fractional ratio for solute in solution. Therefore for ppm, multiply ratio by 1 x 10^6. That is,
(6 x 10^-7/1)(1 x 10^6)ppm = 0.6ppm.

Converting solution concentrations to (gms solute/gms solution) gives a fractional wt/wt ratio that can be converted to % (parts per hundred), ppm or ppb by simply multiplying the ratio by 100 for %, 1-million for ppm, or 1-billion for ppb.

Answer 2

I understand it now, thank you so much!

Answer 3

A very easy way to do these ppm problem in water solution is to remember that 1 ppm = 1 mg/L or 1 ug/mL.
So 0.6 ug/mL = 0.6 ppm.