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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Goddess on May 25, 2005, 07:07:38 PM

Title: Conversion from ppt to ppm
Post by: Goddess on May 25, 2005, 07:07:38 PM
 I need help with a concentration problem:

"A 0.264 g sample of steel containing 8 ppt Cr (ppt = parts per 1000) was dissolved in nitric acid and diluted to 1 L with water. What is the ppm concentration of Cr3+ in the resulting solution?"

My work:

2.64x10^-5 kg steel    x   8 g Cu   x   10^6 ?g  x    1   
                          Kg steel            g            1000ml

=.2112  ?g/ml



The units come out right but I know the answer is wrong.  Am I missing a step or am I completely off base?
Title: Re:Conversion from ppt to ppm
Post by: Borek on May 25, 2005, 07:31:51 PM
Quote from: Goddess on May 25, 2005, 07:07:38 PM
?g/ml

It is ppt, not ppm. ppm is ?g/L.
Title: Re:Conversion from ppt to ppm
Post by: Goddess on May 25, 2005, 07:40:18 PM
I'm sorry, I should have indicated that he wants the answer in ?g/ml.  The problem does say ppm but his units for the answer are as above.

Have I done the calculation right then?

Thanks for the *delete me*
Title: Re:Conversion from ppt to ppm
Post by: Borek on May 25, 2005, 07:54:09 PM
0.264 g is not 2.64x10^-5 kg. 2112 are proper digits, the point is: where point should be? ;)
Title: Re:Conversion from ppt to ppm
Post by: Goddess on May 25, 2005, 07:59:26 PM
Oh crap.  I'll be the one with the dunce cap on in the corner.   :P




Thanks for your *delete me*
Title: Re:Conversion from ppt to ppm
Post by: Garneck on May 30, 2005, 02:54:51 PM
It's ppth, not ppt.

ppt = part per trillion (1012)
Title: Re:Conversion from ppt to ppm
Post by: asqa on July 27, 2005, 05:57:45 AM
Quote from: Borek on May 25, 2005, 07:31:51 PM
It is ppt, not ppm. ppm is ?g/L.

sorry borek
ppm is parts per million is mg/L or ?g/ml
?g/L is ppb i.e. parts per billion


Title: Re:Conversion from ppt to ppm
Post by: Borek on July 27, 2005, 06:30:31 AM
Quote from: asqa on July 27, 2005, 05:57:45 AM
ppm is parts per million is mg/L or ?g/ml
?g/L is ppb i.e. parts per billion

Sorry, my mistake. I know where it did started - g/L is not 1, it is ppt already :(