Mass of ammonia through nitrate concentration problem

1. Jun 11, 2017

Frankenstein19

1. The problem statement, all variables and given/known data
The nitrate concentration in an aquifer is 20 ppm, and its volume is ten million
liters. What mass of ammonia upon oxidation would have produced this mass of
nitrate? [Hint: The moles of nitrogen in reactant and product are identical.]

2. Relevant equations
Possibly 1mg/L & NH3+O2---->NO3-

3. The attempt at a solution
Since 1mg/L equals 1ppm then I'd get a 2*10^8mg for nitrate mass. And NH3+O2---->NO3- (through aerobic contitions and nitrification, idk if this is applicable >: ) then the 1:1 ratio means there's an equal amount of ammonium?

2. Jun 11, 2017

Staff: Mentor

1:1 in terms of moles, not mass.

3. Jun 11, 2017

epenguin

Why not be a bit simpler? You have 20 parts per million, then if you have 1 million, 20 parts of it is 20, 20 parts per million of 10 million is 200!

We have a disagreement there by a factor of 1000.

After you are sure about that, you have to convert the nitrate mass into ammonium mass as Borek and the question itself have indicated.

Do they really use these units? I suppose it is in order to give the general public an idea they can appreciate of the concentrations?

For anyone knowing a bit of chemistry It sounds rather odd - ppm would be okay to give as a formula for somebody to weigh out grams to be put in a lake or something. You can weigh out sodium nitrate or calcium nitrate, but there is no substance called just 'nitrate' that you can weigh out.

4. Jun 11, 2017

Staff: Mentor

Come on, in many places we report things using proxies - like amount of P2O5 in fertilizer. For me NO3- doesn't sound worse than ammonia or just nitrogen, the meaning is obvious