Chapter 4: Nitrogen and Its Compounds

Comprehensive vocabulary flashcards covering the preparation, properties, reactions, and uses of nitrogen, ammonia, ammonium salts, nitrogen oxides, and nitric acid.

Nitride Ion ($N^{3-}$)

An anion formed when a nitrogen atom gains three electrons to achieve a stable octet configuration ($2.5$ to $2.8$), present in ionic compounds such as magnesium nitride ($Mg_3N_2$).

Fractional Distillation of Liquefied Air

The industrial process used to obtain pure nitrogen gas, where air is liquefied under pressure and distilled so that liquid nitrogen boils off first at $-196^{\circ}\text{C}$, leaving behind oxygen which boils at $-183^{\circ}\text{C}$.

Magnesium Nitride ($Mg_3N_2$)

A greenish-yellow solid formed when red-hot magnesium reacts directly with nitrogen gas, which readily hydrolyses in warm water to evolve ammonia gas ($NH_3$).

Haber Process

The industrial method for manufacturing ammonia ($NH_3$) by reacting nitrogen and hydrogen in a $1:3$ volume ratio over a finely divided iron catalyst at about $450\text{--}500^{\circ}\text{C}$ and $200\text{--}500\,\text{atm}$, yielding about $10\text{--}15\%$ ammonia.

Quicklime ($CaO$)

Calcium oxide, used as the drying agent for ammonia gas in the laboratory because ammonia reacts chemically with alternative drying agents like concentrated sulphuric acid and calcium chloride.

Fountain Experiment

A classic laboratory demonstration illustrating the extremely high solubility of ammonia gas in water, where one volume of water can dissolve approximately $700$ volumes of ammonia gas at room temperature and pressure.

Tetraamminecopper(II) Ion ($[Cu(NH_3)_4]^{2+}$)

A deep blue, water-soluble complex ion formed when a precipitate of copper(II) hydroxide ($Cu(OH)_2$) dissolves in an excess of aqueous ammonia solution.

Tetraamminezinc(II) Ion ($[Zn(NH_3)_4]^{2+}$)

A colourless, water-soluble complex ion formed when a precipitate of zinc hydroxide ($Zn(OH)_2$) dissolves in an excess of aqueous ammonia solution.

Smelling Salts

A preparation containing ammonium carbonate ($(NH_4)_2CO_3$), which releases pungent ammonia gas to stimulate breathing and prevent dizziness or fainting.

Nitrogen Monoxide ($NO$)

A colourless, neutral, poisonous gas prepared in the laboratory by reacting copper turnings with $50\%$ nitric acid, which rapidly oxidizes to reddish-brown nitrogen dioxide upon contact with air.

Nitrogen Dioxide ($NO_2$)

A reddish-brown, poisonous gas with a pungent, irritating smell, prepared by the thermal decomposition of lead(II) nitrate ($Pb(NO_3)_2$) or the action of concentrated nitric acid on copper.

Mixed Acid Anhydride

An acidic oxide such as nitrogen dioxide ($NO_2$) that disproportionates in water to form a mixture of two different acids, namely nitric(V) acid ($HNO_3$) and nitric(III) acid ($HNO_2$).

Dinitrogen Tetraoxide ($N_2O_4$)

The dimeric form of nitrogen dioxide that exists as a colourless solid below $-11^{\circ}\text{C}$ and a pale yellow liquid above $-11^{\circ}\text{C}$, which dissociates completely into reddish-brown $NO_2$ gas above $150^{\circ}\text{C}$.

Dinitrogen Monoxide ($N_2O$)

A colourless gas with a faint sickly smell and sweetish taste, commonly known as laughing gas, which rekindles a brightly glowing splinter and is used as a mild dental anesthetic and racecar propellant.

Aqua Fortis

An archaic name for nitric(V) acid ($HNO_3$), translating to 'strong water', given because of its vigorous corrosive action on most metals.

Ostwald Process

The industrial manufacturing method for nitric(V) acid involving the catalytic oxidation of ammonia over a platinum-rhodium catalyst at $700\text{--}900^{\circ}\text{C}$ to form $NO$, followed by oxidation to $NO_2$ and absorption into water.

Passivation

The process whereby metals such as aluminium, chromium, and iron react with concentrated nitric acid to form an impervious oxide surface film that protects the underlying metal from further chemical attack.

Aqua Regia

A highly corrosive fuming liquid mixture consisting of three parts concentrated hydrochloric acid and one part concentrated nitric acid ($3:1$ ratio), utilized to dissolve noble metals such as gold and platinum.

Brown Ring Test

A qualitative analytical test used to detect nitrate ions ($NO_3^-$) and nitric acid, in which concentrated sulphuric acid layered beneath acidified iron(II) sulphate forms a characteristic brown addition compound ring of $FeSO_4\cdot NO$.

Chile Saltpeter ($NaNO_3$)

The common mineral name for sodium nitrate, a poisonous white crystalline compound widely used in solid rocket propellants, fertilizers, matches, and meat curing.

Saltpeter ($KNO_3$)

The common historical name for potassium nitrate, an important chemical agent extensively used in the production of gunpowder and agricultural fertilizers.