[APD] Re: ppm solutions

["Steven Pituch" <spituch at ev1_net>]

Tony said:
>1) you put 100g of NO3 in 100mL of water.  This is INCORRECT.
>2) you put 100g of NO3 in as much water as needed to yield 100mL of
>solution.  THIS is CORRECT.

Yes, I agree with you on this solution (pun!).  However, I think it means
that the measuring cup would need to be filled with the chemical solution.
If most people are like me (and maybe that's stretching things a bit) they
use their kitchen glass Pyrex measuring cup.  So I would prefer to just add
the compound to the water so that only tap water ever touches the cup.
Otherwise, every chemical I mix would need to be poured into the cup to
measure the correct final volume.

Does that make sense?  Maybe I should just go out and buy another measuring
cup.

Anyway I think that people would rather mix a chemical into a given amount
of water than to mix it with less water and then have to bring the volume up
to the required amount, as this would require re-measuring the mixed water.

If the densities at the Merck site are the ones I need then its no problem
changing the calculation.

Steve Pituch


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