Chemical Reaction of Ammonium Chloride and Sodium Nitrite

Study Notes

The +3 oxidation state of arsenic, antimony, and bismuth becomes increasingly stable with respect to disproportionation.

Nitrogen differs from the rest of the group due to its small size, high electronegativity, high ionization enthalpy, and non-availability of d orbitals.
Nitrogen has a unique ability to form pπ-pπ multiple bonds with itself and with other elements having small size and high electronegativity (e.g., C, O).
Nitrogen exists as a diatomic molecule with a triple bond (one s and two p) between the two atoms, resulting in a very high bond enthalpy (941.4 kJ mol).

Nitrogen forms a single N-N bond, which is weaker than the single P-P bond due to high interelectronic repulsion of the non-bonding electrons.
In the solid and liquid states, nitrogen is associated through hydrogen bonds, accounting for its higher melting and boiling points than expected.
The ammonia molecule is trigonal pyramidal with the nitrogen atom at the apex, having three bond pairs and one lone pair of electrons.

Ammonia gas is highly soluble in water, and its aqueous solution is weakly basic due to the formation of OH- ions.
Ammonia forms ammonium salts with acids, e.g., NH4Cl, (NH4)2SO4, etc.
As a weak base, ammonia precipitates the hydroxides (hydrated oxides in case of some metals) of many metals from their salt solutions.
The presence of a lone pair of electrons on the nitrogen atom of the ammonia molecule makes it a Lewis base.

Nitrogen can be obtained by the reaction of NH4Cl with NaNO2, followed by purification steps to remove impurities.
Very pure nitrogen can be obtained by the thermal decomposition of sodium or barium azide.

Dinitrogen is a colorless, odorless, tasteless, and non-toxic gas.
Nitrogen has two stable isotopes: 14N and 15N.
It has a very low solubility in water (23.2 cm3 per liter of water at 273 K and 1 bar pressure) and low freezing and boiling points.
Dinitrogen is rather inert at room temperature due to the high bond enthalpy of the N≡N bond, but its reactivity increases rapidly with a rise in temperature.