math knowledge w/o chem knowledge

[Otavio Exel]

Hi All,

I'm (rather) good with math but poor with chem..

let's say I start a fishless cycle with 5ppm ammonia

after the cycle completes what will be my nitrate concentration?

lessee..

ammonia mass: NH3 -> 7 + 1*3 -> 10
nitrate mass: NO3 -> 7 + 16*3 -> 55

so, assuming the N atoms are all still there in the water..

nitrate concentration: 5 / 10 * 55 = 27.5ppm

am I correct?
or did I miss something?

--
Otavio Exel /<\oo/>\

[Robyn Rhudy]

Otavio, you were right except that the molecular weight of nitrogen is 14
(said another way MW N = 14.0 mol/L).
Therefore, the total MW or NH3 is 17 and that of NO3- is 62 so that 5 ppm
(mg/L) x 62/17 is a final concentration of 18.24 ppm NO3- if ALL the
nitrogen atoms in the original ammonia are now in the nitrate which is NOT
the case as there are other sources and outsources of nitrogen in a real
system.

Robyn - Masters in analytical chemistry
fishpondinfo.com

On Tue, 17 Feb 2004, Otavio Exel wrote:

> Hi All,
>
> I'm (rather) good with math but poor with chem..
>
> let's say I start a fishless cycle with 5ppm ammonia
>
> after the cycle completes what will be my nitrate concentration?
>
> lessee..
>
> ammonia mass: NH3 -> 7 + 1*3 -> 10
> nitrate mass: NO3 -> 7 + 16*3 -> 55
>
> so, assuming the N atoms are all still there in the water..
>
> nitrate concentration: 5 / 10 * 55 = 27.5ppm
>
> am I correct?
> or did I miss something?
>
> --
> Otavio Exel /<\oo/>\
>

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[Charles]

Really minor quibble. The ATOMIC weight of nitrogen is 14, or
thereabouts. Molecular weight is 28. N2 being the most common
molecule.



On Wed, 18 Feb 2004 11:40:03 -0500, Robyn Rhudy >
wrote:

>
>Otavio, you were right except that the molecular weight of nitrogen is 14
>(said another way MW N = 14.0 mol/L).
>Therefore, the total MW or NH3 is 17 and that of NO3- is 62 so that 5 ppm
>(mg/L) x 62/17 is a final concentration of 18.24 ppm NO3- if ALL the
>nitrogen atoms in the original ammonia are now in the nitrate which is NOT
>the case as there are other sources and outsources of nitrogen in a real
>system.
>
>Robyn - Masters in analytical chemistry
>fishpondinfo.com
>
>On Tue, 17 Feb 2004, Otavio Exel wrote:
>
>> Hi All,
>>
>> I'm (rather) good with math but poor with chem..
>>
>> let's say I start a fishless cycle with 5ppm ammonia
>>
>> after the cycle completes what will be my nitrate concentration?
>>
>> lessee..
>>
>> ammonia mass: NH3 -> 7 + 1*3 -> 10
>> nitrate mass: NO3 -> 7 + 16*3 -> 55
>>
>> so, assuming the N atoms are all still there in the water..
>>
>> nitrate concentration: 5 / 10 * 55 = 27.5ppm
>>
>> am I correct?
>> or did I miss something?
>>
>> --
>> Otavio Exel /<\oo/>\
>>
>
>----------------------------------------------------------------
>Important Notice! Robyn's web site has moved from
>http://userpages.umbc.edu/~rrhudy1/ to http://www.fishpondinfo.com. This
>e-mail as well as the old site (which refers to the new site) will be
>deleted on 9/24/04 by UMBC (I have no say in it). After that date,
>please use the e-mail of instead of this e-mail.
>Please spread the word that my site has moved. Thanks.
>
>-----------------------------------------------------------------
>Chemist, preservationist, animal lover, aquarist, and ponder. -
>Extensive web pages on animals, fish, and ponds. -
>http://www.fishpondinfo.com
>Free pond newsletter - sign up at my web site -
>Finally! Buy Robyn's Pond Book at www.1stbooks.com -
>-----------------------------------------------------------------

--

- Charles
-
-does not play well with others