Nitrogen

 

Nitrogen

Chemical formula	N
Atomic Number	7
OTP appearance	colorless gas
Molar Mass(g/mol)	14
Density(g/cc)	0.00125
Melting Point(°C)	-210
Boiling Point(°C)	-195.8
Solubility in water(g/L)	0.02
Speed of sound 20°C, 1atm (m/s)	349
NFPA 704	0 3 0

Under normal circumstances Nitrogen is a fairly inert gas (N₂). It is the primary constituent of air.

Ecological nitrogen cycle

Gaseous nitrogen (N₂) is cleaved by nitrogenase (usually found in single-celled organisms called Diazotrophs) and integrated into the organism's metabolism, usually reentering the ecosystem as ammonia when the organism dies or excretes. Ammonia is absorbed by water and becomes ammonium ions. Ammonium ions are consumed by Nitrosomonas (and others) which convert ammonium ions to nitrite ligands, which are oxidized to nitrates by Nitrobacter (and others). These nitrates can be chemically isolated when bonded to alkali metals.

Ammonia Production
Actor	Source Nitroform	Chemistry	Resultant Nitroform	Timeframe
Nitrogenase in the Diazotroph	Atmospheric N2	2 N2 + 6 H2O → 4 NH3 + 3 O2	Ammonia	Continuously
Urease in bacteria and fungi	Urea	(NH2)2CO + H2O → CO2 + 2 NH3	Ammonia	"a few days"
Nitrate production
Water	Ammonia	NH3 + H2O → NH4- + OH +	Ammonium ions	Immediately
Nitrosomonas	Ammonium ions	NH4- + 2 O2 → NO2- + 2 H2O	Nitrites	"a few weeks"
Nitrobacter	Nitrites	2 NO2- + O2 → NO3-	Nitrates

Uses

Primary

• As an inert gas
• As a source of ammonia via the haber process

Natural occurrence

• As gaseuous N₂ in air
• As a component of urea (CO(NH₂)₂) in animal waste
• As a component of ammonia (NH₃) in decomposed organic waste

Hazards

• Nitrogen asphyxia

Production

Extraction

• from air. See air for separation of nitrogen from air.

Synthesis

sodium nitrate

1. Combine (as dried solids) sodium nitrate and charcoal
2. Heat until molten and charcoal ignites

   4 NaNO₃ + 5 C → 2 Na₂CO₃ + 3 CO₂ + 2 N₂

3. Lead resultant gases through a solution of sodium hydroxide or calcium hydroxide

   N₂(g) + CO₂(g) + 2 NaOH(aq) → Na₂CO₃(aq) + H₂O + N₂(g)

4. Recover the nitrogen gas emerging from the solution.

sodium nitrite

Combine ammonium chloride and sodium nitrite, producing ammonium nitrite and salt. The ammonium nitrite decomposes into nitrogen and water.

NH₄Cl + NaNO₂ → NH₄NO₂ + NaCl

NH₄NO₂ → N₂(g) + 2 H₂O(l)

See Also

• ammonia
• urea