Is there a simple and inexpensive way to generate nitrogen gas?

It's fairly easy to generate a significant yield of hydrogen gas simply by reacting zinc metal with $\ce{HCl}$ or aluminum with $\ce{NaOH}$ solution. But is there a simple and inexpensive chemical reaction that generates a significant yield of pure nitrogen gas?




Per Wikipedia, we have this laboratory method:


$$\ce{NH4Cl(aq) + NaNO2(aq) → N2(g) + NaCl(aq) + 2 H2O (l)}$$


Also per Wikipedia, this method generates small quantities of impurities of $\ce{NO}$ and $\ce{HNO3}$, which can be eliminated by passing the gas through potassium dichromate $\ce{(K2Cr2O7)}$ dissolved in sulfuric acid $\ce{(H2SO4)}$ 


Both ammonium chloride and sodium nitrite are reasonably available chemicals, and the other products (table salt and water) are undeniably safe. Sulfuric acid might a bit tougher to get depending on where you live, and potassium dichromate will be the most difficult given that the use of hexavalent chromium is discouraged (and you should research procedures to reduce the $\ce{Cr2O7^{-2}}$ to $\ce{Cr2O3}$). But otherwise, this looks like the best approach.


 13

You could try a simple two step process. Take some air, burn some carbon-rich material in it until no further burning occurs. Then pass the remaining gas through an alkaline solution to remove the carbon dioxide. The remaining gas will be more than 95% nitrogen.


And you get this with no expensive chemicals. 


 10

One more classic method for $\ce{N2}$ preparation in the lab that hasn't been mentioned yet is oxidative dehydrogenation of ammonia to nitrogen, typically with the help of transition metal oxides, e.g.:


$$\ce{2 NH3 + 3 CuO ->[\pu{500 .. 550^\circ C}] 3 Cu + N2 ^ + 3H2O ^} \tag{1}$$


Reaction with copper(II) oxide is considered canonical and is often listed in textbooks and lab manuals, for example *A Text-book of Practical Chemistry* [1, p. 6] from 1921 describes this process as follows:



> 
> Nitrogen is obtained by passing air first through ·880 ammonia and then over red-hot copper turnings. The oxygen of the air is absorbed by the copper and the resulting copper oxide is at once reduced back to copper by the ammonia. The frequent renewals of the contents of the copper tube are thus entirely avoided.
> 
> 
> \begin{align}
> \ce{2 Cu + O2 & = 2 CuO},\\
> \ce{2 NH3 + 3 CuO & = N2 + 3 H2O}
> \end{align}
> 
> 
> The gas should be washed with sulphuric acid (1 : 4) to free from excess of ammonia, and dried by strong sulphuric acid. The use of dilute acid to free it from ammonia is to avoid the danger of a great rise in temperature should a large excess of ammonia come over.
> 
> 
> 


Method of obtaining nitrogen *via* thermal decomposition of $\ce{NH4NO2}$ is criticized as a rather inconvenient one that may potentially result in an explosion.



> 
> Small quantities of nitrogen may be prepared by carefully heating a solution of ammonium nitrite (sodium nitrite and ammonium chloride in molecular proportions). [...] The method is not recommended as it is difficult to control, and the nitrogen is generally contaminated with oxides of nitrogen, especially when the action becomes violent.
> 
> 
> 


Instead, one can utilize "volcano demo" ([thermal decomposition of ammonium dichromate](https://en.wikipedia.org/wiki/Ammonium_dichromate#Reactions)) as somewhat safer alternative:


$$\ce{(NH4)2Cr2O7 ->[\pu{170 .. 190^\circ C}] Cr2O3 + N2 ^ + 4 H2O ^} \tag{2}$$


These days various sources provide slightly deviating techniques for reaction type (1). Other metal oxides such as $\ce{TiO2}$, $\ce{V2O5}$, $\ce{MnO2}$, their binary and ternary mixtures on silica- and alumina-supported substrates doped with rare-earths (Y, mostly) are capable of selective catalytic oxidation at lower temperatures [2, 3].


### References


1. Hood, G. F.; Carpenter, J. A. A Text-Book of Practical Chemistry; J. & A. Churchill, 1921. ([Google Books](https://books.google.com/books?id=uQ4KAAAAIAAJ&printsec=frontcover&dq=A%20Text-book%20of%20Practical%20Chemistry%20By%20George%20Frederic%20Hood,%20John%20Arthur%20Carpenter&hl=en&sa=X&ved=0ahUKEwijkf_9nubWAhUU24MKHe8dBfAQ6AEIKDAA#v=onepage&q&f=false)).
2. Li, Y.; Armor, J. N. *Applied Catalysis B: Environmental* **1997**, 13 (2), 131–139 DOI: [10.1016/S0926-3373(96)00098-7](http://www.sciencedirect.com/science/article/pii/S0926337396000987).
3. Gang, L.; van Grondelle, J.; Anderson, B. G.; van Santen, R. A. *Journal of Catalysis* **1999**, 186 (1), 100–109 DOI: [10.1006/jcat.1999.2524](http://www.sciencedirect.com/science/article/pii/S0021951799925241).


 5

There is one incredible simple, cheap and easy way to make nitrogen gas with near 99 percent purity if you don't need it compressed. I've used this method in my chemistry experiments when I needed just modest amounts of nitrogen or when I need to do reactions in the absence of reactive oxygen.


Simply buy handwarmers from Walmart or many other sources. Use a heavy duty, large resealable bag and fill it as best you can with regular, uncontaminated air. Drop the hand warmer in there and it will absorb almost all oxygen, leaving you with about 1 percent "all other gases" that are naturally in the atmosphere. Personally, I glue an airtight small rubber tube (a hose from aquarium bubblers, also found at Walmart or any pet store) then clamp it shut with a small but strong spring clamp (although other clamps will due). I've found the hand warmer can dry out before it loses its capacity to absorb O2, so I cut one end open, seal it with laundry clamps (just to keep the contents from spilling out, making a mess) and spray it LIGHTLY now and then with mist from a stray bottle. However, if your not worried about the carbon, iron powder, and table salt contained in these packets (all very harmless) you can cut the packet open and just dump it in the bottom of the bag, and spray as described above once in a while. You would be surprise how long they last and how many bags full of nitrogen you can get from just one hand warmer packet. If you're not worried about adding excess heat to your O2 purged experiment, just put the handwarmer in the bag containing the enclosed beaker. Otherwise, you can purge air out of a different bag, vessel by inserting the hose, and squeezing the nitrogen filled bag.


 5

According to [Wikipedia](http://en.wikipedia.org/wiki/Nitrogen#Production) you can generate pure nitrogen by heating metal azides, which gives out 
nitrogen and the metal. Sodium azide is [not really expensive](http://www.sigmaaldrich.com/catalog/product/sial/s2002).


$$\ce{2NaN\_3 ->2Na + 3N\_2}$$


However, as you may expect, this may not be a very safe reaction as the first reaction that came to my mind when you asked for a reaction with large yield of nitrogen gas is that of TNT, though that would not give a pure yield as you have required. Azides are also explosive. Sodium azide is [used in car airbag and airplane escape chutes](http://en.wikipedia.org/wiki/Sodium_azide#Automobile_airbags_and_airplane_escape_chutes) where this exact reaction is used to quickly inflate these safety features. The metallic sodium formed is then further reacted to less dangerous sodium compounds. 


 4

To generate nitrogen you could mix potassium nitrate, hydrochloric acid, and zinc.
It would generate nitrogen and the byproducts will be zinc chloride, ammonium chloride, and potassium chloride.
The nitrogen would be mixed with some HCl vapors, which you could remove through bubbling it in water.


The combustion of dinitrogen monoxide can also produce nitrogen.


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Thermal decomposition of ammonium nitrite:
$$\ce{NH4NO2 -> N2 + H2O}$$


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Ammonium Dichromate reacted with heat produces only one gaseous product, Nitrogen. FIlter through a bubbler to get particles out of it. See Wikipedia under Ammonium Dichromate for the reaction equation and stoichiometry.


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