On Mon, 28 Oct 1996, Marque Crozman wrote:
>
> Something that I cant get out of my mind was a talk by Richard Carlson
> at the conference, where he referred to the units of ppm and mg/l being
> approximately the same.
>
> This has been bothering me for some time, as the Dupla Fe test kit
> measures Fe in mg/l and the Aquasonic test kit measures Fe in ppm.
They really are the same to all intents and purposes.
>
> 322.4 ions of Fe for every 1millon parts of Fe ions and water molecules.
>
> ie: 1mg/l = 322.4 ppm.
>
> If my analysis is correct :-?, these quantities are not similar at all, or have I missed the
> bucket completely and covered myself with 10 litres of water or 335E25 molecules of H20
You are a long way out because the ppm scale is a weight based scale and
not a molar based one. One gram in one million grams is one part per
milion. A miligram or 1/1000 of a gram in one litre (approx 1000g) is
also one part per milion. The approximate bit is the fact that the water
needs to be at exactly the right tempterature to really weigh 1Kg per L.
Peter Hughes
ANGFA ACT
Peter,
You could possibly be right, but from what I know about gas measurement
when measuring in ppm, you are talking about a volumetric measurement, and therefore
a molar measurement, as there are a given number of gas molecules present in a given
volume, providing the temperature and pressure are held constant.
'
I cannot comment that the same is however true for liquids. That is why I raised the
question. And further more, if you are correct for liquids and I am correct for the case
of gasses, why is there this fundamental difference?
Marque APD - ANGFA - NSW
:->