Why nitrous oxide and nitric oxide are neutral gases?

Nitrogen forms lot of oxides. Some of them are neutral, and some are acidic. Also nitrogen forms basic compounds such as ammonia. In this tutorial, we are going to learn why nitrous oxide (N2O) and nitrogen oxide (NO) are neutral.

Neutral oxides of nitrogen

Nitrous oxide (N2O) and nitrogen oxide (nitric oxide / NO) are neutral gases of oxides of nitrogen. These two nitrogen oxides do not react with water to form oxoacids such as HNO2 or HNO3.

Now we have to disucuss, why some of these oxides are neutral?

Oxidation numbers of nitrogen in N2O and NO

  1. N2O : +1
  2. NO : +2

Neutral oxides

Neutral oxides do not form acids or bases in aqueous solutions. Oxoacids of nitrogen are HNO2 or HNO3 acids.

Oxidation number of nitrogen in nitrous oxide and nitrogen oxide are less than other oxides of nitrogen.

Oxides of nitrogen

Nitrogen forms so many oxides and they have very different characteristics. Those oxides are noted below.

  • N2O - nitrous oxide
  • NO - nitric oxide
  • N2O3 : dinitrogen dioxide
  • NO2 :dNitrogen dioxide
  • N2O4 : dinitrogen tetroxide
  • N2O5 : dinitrogen pentoxide
Preparing, Reactions of Oxides of Nitrogen

Acidic properties and oxidation number

When oxidation number of nitrogen in respective oxides increases, acidic properties are increased too.

Oxides which have +3 or higher oxidation number of nitrogen will show acidic property and react with water to form oxoacid such as nitrous HNO2 and nitric acids HNO3.

nitrous acid HNO2

nitric acid HNO3

Oxidation numbers of oxides of nitrogen

  • N2O - +1
  • NO - +2
  • N2O3 : +3
  • NO2 : +4
  • N2O4 : +4
  • N2O5 : +5

Therefore N2O3, NO2, N2O4, N2O5 are acidic gases.


Why Carbon monoxide and nitric oxide are neutral oxides?

To give a acidic solution the compound should have an ability to release hydronium ion. For that, water should be hydrolyzed and should form hydronium ion. But polarization of atoms of nitrogen dioxide and carbon monoxide is not enough to hydrolyze water. So they are neutral oxides.

Is N2O a neutral gas?

Yes, as previously described, N2O is a neutral gas. No any acid is formed when N2O is sent to the water.

Is oxidation number a factor for acidic properties?

Yes. When oxidation number increases, acidic characteristic increases. As an example, we can compare nitrous acid (HNO2) and nitric acid (HNO3). Oxidation number of nitrogen in nitrous acid is +3. Oxidation number of nitrogen in nitric acid is +5. Nitric acid is a strong acid and nitrous acid is a weak acid.

What are the neutral oxides? Give examples.

Carbon monoxide (CO) is a neutral oxide. N2O and NO are neutral oxides of nitrogen.

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Oxidation Numbers of Elements in Periodic Table