[brunetteangel]

So, here's my problem.

Calculate how much HNO3 you can get (theoretically) from 1000 cubic meters of NH3.

Now, the only way of getting HNO3 using NH3 is this one:

4NH3 + 5O2 -> 4NO + 6H20
2NO + O2 -> 2NO2
3NO2 + H2O -> 2HNO3 + NO

So I thought I could do it this way:

from 4NH3 I get -> 2 HNO3
so, from 89,6 cubic dm of NH3 I get -> 126,0256g of HNO3
then, from 1.000.000 cubic dm of NH3 I will get -> x (unknown mass) of HNO3

But the problem is, I get the wrong result when I calculate it. I get 1.406, 53 kg and the solution at the end of the book says 2.812,5 kg.

Please tell me where I made mistakes. Thanks.

[Essay]

brunetteangel, on 13 January 2012 - 10:00 PM, said:

So, here's my problem.

Calculate how much HNO3 you can get (theoretically) from 1000 cubic meters of NH3.

Now, the only way of getting HNO3 using NH3 is this one:

4NH3 + 5O2 -> 4NO + 6H20
2NO + O2 -> 2NO2
3NO2 + H2O -> 2HNO3 + NO

So I thought I could do it this way:

from 4NH3 I get -> 2 HNO3
so, from 89,6 cubic dm of NH3 I get -> 126,0256g of HNO3
then, from 1.000.000 cubic dm of NH3 I will get -> x (unknown mass) of HNO3

But the problem is, I get the wrong result when I calculate it. I get 1.406, 53 kg and the solution at the end of the book says 2.812,5 kg.

Please tell me where I made mistakes. Thanks.

I notice that your answer is exactly half of the expected. That should be a good clue!

Dig in to these most important of reactions for bacteria; nitrifying denitrifiers & denitifying nitrifiers... assimilatory and dissimilatory nitrification!


...or words to that effect.

~

[John Cuthber]

"Dig in to these most important of reactions for bacteria; nitrifying denitrifiers & denitifying nitrifiers... assimilatory and dissimilatory nitrification!"
Or just count the nitrogen atoms.

[brunetteangel]

Oh thanks.
But I tried counting the nitrogen atoms again, but the solution always comes out to be 1406,53 kg. :/
And should I use all 3 formulas or just the proportion?

[Essay]

brunetteangel, on 14 January 2012 - 09:16 AM, said:

And should I use all 3 formulas or just the proportion?

...not sure I follow, but those equations are not balanced between each other (if that makes sense) and so yes? you do need to account (adjust) for the proportions? ...in all 3.

Does that give you a different way of looking at it?


~

p.s. ...in other words, those equations are not meant to describe the input and output of a particular metabolic pathway. They are just 3 philosophical statements that can be related to each other in various ways and circumstances; not a unified input/output statement.

This post has been edited by Essay: 14 January 2012 - 10:00 AM

[John Cuthber]

Essay, on 14 January 2012 - 09:53 AM, said:

...not sure I follow, but those equations are not balanced between each other (if that makes sense) and so yes? you do need to account (adjust) for the proportions? ...in all 3.

Does that give you a different way of looking at it?


~

p.s. ...in other words, those equations are not meant to describe the input and output of a particular metabolic pathway. They are just 3 philosophical statements that can be related to each other in various ways and circumstances; not a unified input/output statement.

Why are you talking about metabolism?
http://en.wikipedia....rial_production

The NO produced in the 3rd reaction is recycled to the second.
So, all the nitrogen atoms from ammonia end up in the nitric acid.
How many nitrogen atoms are there in 1000 cubic metres of ammonia?
How much nitric acid contains that number of atoms of nitrogen?
How much does that much acid weigh?

[Essay]

John Cuthber, on 14 January 2012 - 10:58 AM, said:

Why are you talking about metabolism?
http://en.wikipedia....rial_production

From an ecological perspective, these reactions are important to the source of our sustenance. But I only mentioned metabolism with respect to how the 3 OP equations were NOT presented. I should have added that they also are written NOT to show any particular industrial (input/output) process either. They are general chemical statements that could be applied to understand either metabolic or industrial processes, right?

~

[John Cuthber]

Essay, on 14 January 2012 - 11:12 AM, said:

From an ecological perspective, these reactions are important to the source of our sustenance. But I only mentioned metabolism with respect to how the 3 OP equations were NOT presented. I should have added that they also are written NOT to show any particular industrial (input/output) process either. They are general chemical statements that could be applied to understand either metabolic or industrial processes, right?

~

I can't help thinking that this
"Dig in to these most important of reactions for bacteria; nitrifying denitrifiers & denitifying nitrifiers... assimilatory and dissimilatory nitrification!"
was unhelpful to the OP.
All the understanding in the world of the bacteria won't answer the question so it's a bit of a red herring.

[brunetteangel]

John Cuthber, on 14 January 2012 - 11:10 AM, said:

Why are you talking about metabolism?
http://en.wikipedia....rial_production

The NO produced in the 3rd reaction is recycled to the second.
So, all the nitrogen atoms from ammonia end up in the nitric acid.
How many nitrogen atoms are there in 1000 cubic metres of ammonia?
How much nitric acid contains that number of atoms of nitrogen?
How much does that much acid weigh?

I think I got it, thanks to your questions.

1) in 89,6 cubic dm of ammonia there are 4 nitrogen atoms
=>in 1.000.000 cubic dm of ammonia there are 44.642,85714 nitrogen atoms


2) 1 mol of nitric acid contains 1 nitrogen atom
=>44.642,85714 mol of nitric acid contains 44.642,85714 nitrogen atoms


3) 1 mol of nitric acid weighs 63,0128 g
=>44.642,85714 mol of nitric acid weigh 2.813.071,428 g, that is, 2.813 kg


Thanks to both of you for helping.

[Essay]

John Cuthber, on 14 January 2012 - 01:21 PM, said:

I can't help thinking that this
"Dig in to these most important of reactions for bacteria; nitrifying denitrifiers & denitifying nitrifiers... assimilatory and dissimilatory nitrification!"
was unhelpful to the OP.
All the understanding in the world of the bacteria won't answer the question so it's a bit of a red herring.

You're right! It was a bad pun about agriculture and the soil bacteria that convert ammonia into "plant-available" nitrates. I hope the OP didn't think the answer lay buried in the literature about this or nitrogen fixation.

I was recently surprised to learn, however, that:

"Despite application of luxurious amounts of N and use of refined best management practices, crops still acquire 40-80 percent of their N from endogenous soil reserves, and an average of 50 percent of the N applied is lost from agricultural landscapes. --p.137
The Rhizosphere: An Ecological Perspective Edited by Cardon & Whitbeck; Elsevier Science, Hardbound,
232 Pages; Published: MAR-2007; Imprint: ACADEMIC PRESS. LC Call #: QK644 .R445 2007

This "lost" nitrogen is a large source of GHG pollution, as well as creating "Dead Zones" (and future oil shales?) in our coastal waters and fisheries, so it's an important topic.

And I was happy to see someone learning about the reactions that supply those still important "endongenous soil reserves," supporting our food supplies, so I got carried away.

The mention of a 2x factor didn't seem to be relevant either, so thanks for keeping the focus on useful results. A little color commentary can be nice, but it can be distracting too; so I'll try to tone it down a bit moving forward. Thanks for the help.
===


"Clearly, greater reliance on plant-mediated mineralization for nutrient acquisition in agroecosystems would reduce the potential for nutrient losses due to the tight coupling betwen the release of soluble, potentially mobile nutrient forms and plant uptake in the rhizosphere. This could be particularly advantageous in the case of N, which is highly susceptible to loss once it is converted to inorganic forms. Inorganic N pools can be extremely small while high rates of net primary productivity (NPP) are maintained if N-mineralization and plant assimilation are spatially and temporally connected in this manner." --p.137

Wow, anyone could become rich by inventing something to connect those processes spatially and temporally, in that manner. Or they could use biochar, which does that naturally, and cuts nitrous oxide emission up to 50% ([2007] David Laird, USDA National Soil Tilthe Laboratory).

~

Thanks again for making sure something more immediately helpful was conveyed.

This post has been edited by Essay: 15 January 2012 - 03:42 AM