Nitrous oxide,nitric oxide, dinitrogen trioxide, nitrogen dioxide, dinitrogen tetroxide, dinitrogen pentoxide | nitrogen oxides reactions|properties|effects

Nitrogen has different oxides because nitrogen has different oxidation numbers.
Usually nitrogen has oxidation numbers from -3 to +5.
But oxidation number of nitrogen in oxides of nitrogen varies from +1 to +5 because nitrogen's electronegativity is less than oxygen.

Oxides of nitrogen

Nitrous oxide - N2O

Nitric oxide - NO

dinitrogen trioxide - N2O3

nitrogen dioxide - NO2

dinitrogen tetroxide - N2O4

dinitrogen pentoxide - N2O5



Oxidation numbers of oxides of nitrogen

Nitrous oxide (N2O) : +1

Nitric oxide (NO) : +2

dinitrogen trioxide (N2O3) : +3

nitrogen dioxide (NO2) : +4

dinitrogen tetroxide (N2O4) : +4

dinitrogen pentoxide (N2O5) : +5

Electronegativity of oxygen(3.5) is higher than nitrogen(3.0). So electrons in the bond between oxygen and nitrogen is attracted towards oxygen atoms. Therefore O is polarized as negatively and nitrogen is positive. When number of O atoms increases oxidation number of N atom increases. When oxidation number increases, acidic characteristics also increases.


Phenomenons of nitogen oxides formation

Nitrogen oxides is formed when oxygen reacts with nitrogen in air at the high temperatures inside an automobile engine. This is called thermal nitric oxide. Also nitrogen oxides can be formed due to lightning in the sky.



Nitrous oxide / dinitrogen monoxide / nitrogen(i) oxide / N2O

Oxidation number of nitrogen is +1. Nitrous oxide is relatively soluble in water. Nitrous oxide is used as an anesthetic (laughing gas). It has a linear structure.

nitrous oxide molecule shape

Resonance structures of nitrogen(i) oxide

Three resonance structures can be drawn for nitrous oxide.

resonance structures of nitrous oxide

Properties of Nitrous oxide|nitrogen(i) oxide

  • relatively soluble in water
  • A neutral gas
  • A supporter of combustion ( release O2 when heat )

Preparing nitrous oxide|N2O


Heat ammonium nitrate ( NH4NO3 )

Nitrous oxide (N2O) and water forms as the products.

ammonium nitrate thermal decomposition

Heat mixture of sodium nitrate( NaNO3 ) and ammonium chloride( NH4Cl )

NaNO3 and NH4Cl will give NH4NO3. When heat the mixture, N2O forms.

sodium chloride and ammonium chloride thermal decomposition



Nitric oxide / nitrogen(ii) oxide / nitrogen monoxide / NO

Nitric oxide is prepared in Ostwald process which produce nitric acid industrially. Oxidation number of N in nitrogen(ii) oxide is +2. NO is easily oxidized into NO2. Nitric oxide is linear molecule.
2NO + O2 → 2NO2

nitric oxide molecule shape

nitric oxide and oxygen reaction

NO reacts with O2 and becomes NO2 easily.

Nitric oxide and oxygen in the air reaction

Properties of nitric oxide

  • A neutral gas
  • Colourles

Preparing nitric oxide|NO

Following reactions can be used to produce nitric oxide in the laboratory.


Copper and dilute nitric acid reaction

Copper and dilute nitric acid reaction give nitric oxide(NO), copper nitrate( Cu(NO3)2), and water as products.

copper and nitric acid reaction

Decomposition of nitrous acid

At low temperature, slow decomposition of nitrous acid gives nitric acid and nitric oxide(NO)

Decomposition of nitrous acid

Nitric oxide formation in nitric acid manufacturing(ostwald process)

Ammonia(NH3) gas and oxygen(O2) are used as raw materials to manufacture nitric(HNO3) gas industrially. In the first step of nitric acid manufacturing, nitric oxide(NO) is formed by reaction of NH3 and O2 in 850 - 10000C temperature. That mixture(NH3 and O2 ) is sent through Pt/Rh catalyst. Then exothermic reactions happens and produces NO and H2O . Due to exothermic reaction, reaction happens easily after it was started.
4NH3(g) + 5O2(g) → 4NO + 6H2O(g) + ΔH






dinitrogen trioxide|nitrogen(iii) oxide|N2O3 preparing and reactions

Dinitrogen trioxide can behave as a 1:1 mixture of NO and NO 2 . In the gas phase, N2O3 dissociates to give NO and NO2. At 20 to 300C the reverse reaction can be used to prepare N2O3.

dinitrogen trioxide molecule shape

Properties of dinitrogen trioxide

  • Weak acidic

dinitrogen trioxide and water reaction

N2O3 reacts with water and produce nitrous (HNO2) acid solution.

dinitrogen trioxide and water reaction

Preparing nitrous oxide|N2O3

nitric oxide and nitrogen dioxide reaction

Mix nitric oxide (NO(g) ) gas and nitrogen dioxide (NO2(g)) gas. Cool the mixture. N2O3forms.

prepare dinitrogen trioxide




nitrogen dioxide / nitrogen(iv) oxide / NO2

Nitrogen dioxide molecule is bent shape. NO2 is an acidic, brown, and a very toxic gas. Brown colour of NO2 gas can be seen in high traffic cities(this incident is defined as photochemical smog).

nitrogen dioxide molecule

Nitrogen dioxide and water reaction

Nitrogen dioxide and water reacts and produce nitrous (HNO2) nitric (HNO3) acids. This is a one of main step in nittric acid manufacturing(ostwald method)

nitrogen dioxide with water reaction


Prepare nitrogen dioxide


Hot concentrated nitric acid and copper reaction

Add hot concentrated nitric (HNO3) acid into copper. NO2, Cu(NO3)2 and water are given as products.

Hot concentrated nitric acid and copper reaction

Decomposition of nitric acid

When nitric acid is heated or exposed to the sun light it turns yellow owing to it's decomposition . The yellow colour observed in bottles of nitric acid is due to the formation of nitrogen dioxide(NO2).

Decomposition of nitric acid




dinitrogen tetroxide/ N2O4

An acidic , colourless gas.

dinitrogen tetroxide N2O4 molecule

dinitrogen tetroxide and water reaction

Reacts with water and produce nitrous (HNO2) nitric (HNO3 ) acid

dinitrogen tetroxide N2O4 and water reaction

Prepare dinitrogen tetroxide|N2O4


Prepare dinitrogen trioxide from nitrogen dioxide

>Cool NO2 gas, and pressurize it. Then NO2 becomes into N2O4

prepare dinitrogen tetroxide N2O4




dinitrogen pentoxide|N2O5

Dinitrogen dioxide is a white solid which sublimes at 320C. N2O5 is a good oxidizing agent because the oxidation state of nitrogen in this oxide being +5. It is Anhydrate of nitiric acid.

dinitrogen pentoxide N2O5 molecule

dinitrogen pentoxide and water reaction

Reacts with water and produce nitric (HNO3 ) acid.

dinitrogen pentoxide N2O5 with water reaction

Prepare dinitrogen pentoxide/ N2O5

Dehydration at low temperatures

Dinitrogen pentaoxides can be prepared by dehydration at low temperatures

prepare dinitrogen pentoxide N2O5


Effect of nitrogen oxides to the environment

Nitric oxide(NO) and nitrogen dioxide has a very large effect on photochemical smog. Oxides of nitrogen include in automobile exhaust and emits to the environment. NO reacts with O2 to form nitrogen dioxide(NO2). a yellowish brown gas. Again NO2 absorbs energy from sunlight and breaks up into nitric oxide(NO) and free reactive oxygen atom. These free oxygen atoms are very reactive and causes to form a large number of free organic radicals. This organic free radicals results into a number of chain reactions producing many undesirable compounds such a formaldehyde, acrolein, organic peroxide, organic hydroperoxides, peroxyacyl nitrates.




Effect of nitrogen dioxide to acid rain

NO2 reacts with water and forms HNO3 acid which comes down as the acid rain.

Effect of nitrogen dioxide to acid rain


Is nitrogen dioxide a neutral gas?

No. Nitrogen dioxide(NO2) dissolves in water and react with water to give nitric acid(HNO3) which is a strong acid. But N2O and NO are neutral gases.

Acidic properties of oxides of nitrogen

acidic_properties_of_oxides_of_nitrogen

Questions of oxides of nitrogen

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Is nitrogen dioxide a neutral gas?

No. Nitrogen dioxide(NO2) dissolves in water and react with water to give nitric acid(HNO3) and nitrous acid(HNO2). HNO3 is a strong acid. But N2O and NO are neutral gases.



More oxides of nitrogen releasing reactions


NO2 releasing


Lead and nitric acid reaction

Lead(Pb) and dilute nitric acid react to form Pb(NO3)2, NO2 and water.

Pb and nitric acid reaction


Hot concentrated nitric acid and carbon reaction

Carbon(C) and hot concentrated HNO3 acid react to give CO2, NO2, H2O.

Hot concentrated nitric acid and carbon reaction

Hot concentrated nitric acid and sulfur reaction

Sulfur(S) and hot concentrated HNO3 acid react to give H2SO4, NO2, H2O.

Hot concentrated nitric acid and sulfur reaction

Nitric acid and phosphorus reaction

Phosphorus(P) and HNO3 acid react to give H3PO4, NO2, H2O.

Nitric acid and phosphorus reaction


NO releasing


Nitric acid and silver metal reaction

Ag react with HNO3 acid to give AgNO3, NO2 and H2O.

Nitric acid and silver metal reaction

Nitric acid and hydrogen sulfide(H2S) reaction

S and NO are given as the products by the reaction of H2S and HNO3.

Nitric acid and hydrogen sulfide reaction

Questions asked by students


Is nitric oxide more electronegative?

Electronegativity is increased when s orbit characteristics are increased. Therefore an atom with sp orbital hybridisation has a higher electronegativity than sp2 orbital hybridisation.