Nitrogen

[Miss Wiggle]

OK bear with me, I'm sure this stuff is dead simplistic for you guys, but I'd like to develop my technical/scientific knowledge a bit.

I'm trying to understand nitrogen a bit better.

Nitrite and nitrate are both forms of nitrogen aren't they?
Is ammonia a form of nitrogen as well?

Whats the difference between them all, I guess it's nitrogen with molecules of other things attached to them..... but what exactly? As nitrate is less toxic I assume it's more dilluted with other molecules...... or is that not how it works?!

when we talk about nitrite and ntirate in our aquariums they are in a liquid form right?

i know to do some fancy scientific type tricks people often use liquid nitrogen, what's this in relation to the liquid forms of nitrogen in our tanks?

OK that's probably some slightly random questions not phrased very well, but hopefully one of you can start to explain it all to me!!

 

[andywg]

The element Nitrogen is the most abundant gas in the atmosphere, making up around 79% of the air.

And now after a quick read I shall have a go at explaining a bit further.

According to Wikipedia it has a boiling point of 77.36K (-195.79 C), though this is for the pure nitrogen rather than once it is with other atoms.

If you look through wikipedia's pages on ammonia/ammonium, nitrite and nitrate you will see that ammonia is NH3 and a weak base but when dissolved in water it wil react with hydrogen ions to form NH4+ (ammonium).

Once bacteria oxidise ammonia it becomes nitrite (NO2-) and once this is oxidised it becomes NO3-.

It appers that nitrite and nitrates are salts or esters whilst ammonia is normally a gas in the atmosphere but can dissolve in water.

So, nitrite and nitrates both contain nitrogen, but due to their interaction with other elements they exhibit different qualities.

 

[Miss Wiggle]

Thanks Andy,

ooooooh i feel some GCSE chemistry coming back to me - So is NO2 one atom of Nitrogen and two of Oxygen and NO3 one of nitrogen and three of oxygen, so essentially the same thing but a bit more dilluted (probably not the right term but i think you know what i'm trying to get at)?

What is an ester?

so if nitrite and nitrate are salts, then they are effectivley dissolved in the water in our tanks? do they fully dissolve or is it likely that you'd have some solid residue floating around somewhere.

that just got me thinking, waterdrop who posts in the new to the hobby section a lot has a sort of theory that nitrate can hang around in clumps rather than being equally distributed through the water as sometimes a large water change will not reduce nitrate proportionally as you would expect it too. Now I know you'll immediately call into question the accuracy of nitrate test kits, but bearing in mind the nature of nitrate is this practically possible or not?

I know water can have a saturation point with some things where it can't dissolve anymore of whatever it is into it so you'll be left with some solid, is this the case here?

 

[waterdrop]

OK, coupla' things:

MW wrote:

"when we talk about nitrite and ntirate in our aquariums they are in a liquid form right?
i know to do some fancy scientific type tricks people often use liquid nitrogen, what's this in relation to the liquid forms of nitrogen in our tanks?"

When you strart studying elements and molecules and their charges, you quickly realize that a lot of the above stuff is about the interpretation of the words. When people say one of these gases (their natural state) is "in liquid form," they usually mean its in the "physical state of being a liquid," so it must be down at a combination of temperature and pressure (very cold for nitrogen as you can see from Andy's mention of the boiling point) that allows it to be a liquid. This is quite different from the Nitrogen atoms being bound up with other elements, forming molecules, and being surrounded by still different molecules, thus being "dissolved" in, say, water.

Thus, you've actually asked a rather interesting question, one that no doubt might be heard in a high school or college chemistry class: Is it correct to refer to the elemental nitrogen bound up in molecules and dissolved in water as being "liquid?" A good teacher could probably enlighten us with a really good answer to that and perhaps some of our good chemistry members will!

(To connect it to my previous paragraph, I think we can see that its semantics, since the composition of the nitrogen atom stays the same except for the movement/charge behaviour of its outer electrons as they interact with the outer electrons of the other associated atoms (ex. oxygen and hydrogen atoms.)... this "interacting of charges" being the basis of chemistry and indeed of most all the interacting we see on earth, lol [Have you ever thought about the fact that -everything- that we see, touch, smell (...sense in other words), are basically the up and down quarks that make up the protons of the nucleous' of our elements and that they've been frozen into those little relationships with each other ever since the "Big Bang!" at the beginning of time?? (stuck there by the "strong force" described in physics) something like that anyway, really cool!])

~~waterdrop~~

 

[Miss Wiggle]

so if a solid is dissolved into a liquid it's not technically in it's liquid form?

 

[waterdrop]

MW, its complicated to reply! Try reading the 3 entries in wikipedia entitled "state of matter", "liquid", and best of all "fluid" These are pretty good for getting you thinking about the differences between the terms liquid, fluid and mixture, I guess.

~~waterdrop~~

 

[Miss Wiggle]

OK, about to finish work, will have a look at wiki later

 

[Dave Spencer]

So is NO2 one atom of Nitrogen and two of Oxygen and NO3 one of nitrogen and three of oxygen, so essentially the same thing but a bit more dilluted (probably not the right term but i think you know what i'm trying to get at)?

Despite the apparent difference being only one atom of oxygen, NO2- and NO3- have very different characteristics. As you know, NO2- is very toxic, and not a great deal of use to predominantely fish based tanks, or plant based tanks. The extra oxygen associated with NO3- does not mean that the toxicity is diluted, although I think I can see where you are coming from.

so if nitrite and nitrate are salts, then they are effectivley dissolved in the water in our tanks? do they fully dissolve or is it likely that you'd have some solid residue floating around somewhere.

NO2- and NO3- come in the form of dissolved inorganic nitrogen (DIN from salts), or dissolved organic nitrogen (DON from filtration, fish waste etc.). DON are accompanied by a complex carbon molecule (struggling to remember here). When you read about fertilising tanks with nitrates, it is with KNO3, which is a salt (DIN). I digress, but it is the DIN fraction that is most accessible to plants, not the DON. This why it is not necessarily a good idea to recommend plants for nitrate control, as it will be the DON fraction that people are trying to reduce.

that just got me thinking, waterdrop who posts in the new to the hobby section a lot has a sort of theory that nitrate can hang around in clumps rather than being equally distributed through the water as sometimes a large water change will not reduce nitrate proportionally as you would expect it too. Now I know you'll immediately call into question the accuracy of nitrate test kits, but bearing in mind the nature of nitrate is this practically possible or not?

I don`t believe nitrates are evenly distributed throughout larger tanks. I have recently delved in to the world of an almighty 120cm , and have observed how difficult it is to distribute CO2 evenly. I would assume all other water borne nutrients, toxins etc. are the same.

I know water can have a saturation point with some things where it can't dissolve anymore of whatever it is into it so you'll be left with some solid, is this the case here?

Yep! I use a calculator that lets me know the maximum amount of KNO3 I can dissolve in 500ml of water when I mix ferts.

Dave.

 

[Miss Wiggle]

interesting, thanks Dave

yeah the first point, i thought that because both nitrite and nitrate are toxic but at different levels so if one's got more of something in than the other it feels like it's dilluted.

but happy to admit defeat if that's not the case, my chemistry/physics knowledge is far from the best, just trying to learn and get my head around stuff.

so is water with nitrate in likely to be at the top or bottom of the tank? to try and get an accurate reading where in the tank should we take a water sample from?

so whats the maxiumum amount (in ppm if possible) of nitrate you can have? whats the saturation point.....

 

[aaronnorth]

so is water with nitrate in likely to be at the top or bottom of the tank

I belive i have read it is mainly at the bottom, possibly due the density,

so whats the maxiumum amount (in ppm if possible) of nitrate you can have? whats the saturation point....

It is high, and it gets higher as the temperature increases.

 

[waterdrop]

MW wrote:

so if nitrite and nitrate are salts, then they are effectivley dissolved in the water in our tanks? do they fully dissolve or is it likely that you'd have some solid residue floating around somewhere.

that just got me thinking, waterdrop who posts in the new to the hobby section a lot has a sort of theory that nitrate can hang around in clumps rather than being equally distributed through the water as sometimes a large water change will not reduce nitrate proportionally as you would expect it too. Now I know you'll immediately call into question the accuracy of nitrate test kits, but bearing in mind the nature of nitrate is this practically possible or not?

Just a note that solid residues or clumps was not ever what I was visualizing when I posted these speculations. My wondering was more about what Aaron has mentioned:

I belive i have read it is mainly at the bottom, possibly due the density,

And I find it interesting that Dave is mentioning some similar thoughts:

I don`t believe nitrates are evenly distributed throughout larger tanks. I have recently delved in to the world of an almighty 120cm , and have observed how difficult it is to distribute CO2 evenly. I would assume all other water borne nutrients, toxins etc. are the same.

But none of this feels very satisfactory yet. To me it still feels like someone who knows more of the chemistry stuff of solutions and such is going to come along and either shoot this all down, saying the NO3 has got to be distributed evenly or else is going to have some other explanation for why we are getting the "hunches" we are expressing.

Doesn't it feel that way to you guys too???

~~waterdrop~~

 

[Dave Spencer]

But none of this feels very satisfactory yet. To me it still feels like someone who knows more of the chemistry stuff of solutions and such is going to come along and either shoot this all down, saying the NO3 has got to be distributed evenly or else is going to have some other explanation for why we are getting the "hunches" we are expressing.

Doesn't it feel that way to you guys too???

~~waterdrop~~

These are not hunches WD, these are obsevations. I can see in my 120cm tank where the dropper is nigh on yellow (I move it around the tank, too), and the Copper harlequins are telling me I am overdoing the CO2, I still get staghorn and Spirogyra. I have added a Koralia powerhead, which solves the problem in the area it is pointed, but I find now that the algae moves elsewhere.

I can trigger staghorn at will, by simply turning off the CO2 in my tank. I have done this more than once, too.

A tank of this size is a new experience for me, but I have x15 turnover, and feel I will need to take it up further. This is a tank with fairly complex planting and hardscape, so getting distribution right is difficult. No way are all the nutrients evenly distributed.

As you know, I have a bit of an affinity with test kits, but I also have one with "scientists" too. These are the guys who are quoted by people who believe excess nutrients of various kinds are causing algae in our tanks, yet I and many others prove this to be wrong on a daily basis.

I rely heavily on my observational skills, and draw some reasoning from what I see. Personally, I couldn`t care less when somebody quotes work done by a scientist in the back waters of Florida. It isn`t relevant to my tanks.

I have the made the correlation that due to the evident lack of uniform CO2 distribution in my larger tank, it would be fair to assume other nutrients are not evenly distributed.

Dave.

 

[Miss Wiggle]

Just a note that solid residues or clumps was not ever what I was visualizing when I posted these speculations. My wondering was more about what Aaron has mentioned:

Yeah when I wrote that I thought I wasn't explaining your thoughts very well!